MCQ (Practice) - Reproductive System (Level 1) - Class 12 MCQ

Outer coat of seminiferous tubules is composed of fibrous connective tissue called Tunica propria.
The seminiferous tubules are an essential component of the testes, responsible for the production and maturation of sperm. The outer coat of the seminiferous tubules, known as the tunica propria, consists of fibrous connective tissue that provides structural support and protection. Let's break down the answer further:
Tunica propria:
- The tunica propria is the outermost layer of the seminiferous tubules.
- It is composed of fibrous connective tissue.
- The fibrous connective tissue provides structural support and protection to the seminiferous tubules.
- It helps maintain the shape and integrity of the tubules during the production and maturation of sperm.
Lamina propria:
- Lamina propria refers to the connective tissue layer found in various organs, including the respiratory and urinary tracts.
- It is not specifically associated with the outer coat of seminiferous tubules.
Plica semilunaris:
- Plica semilunaris refers to a fold of conjunctiva in the inner corner of the eye.
- It is unrelated to the structure of the seminiferous tubules.
Tunica albuginea:
- The tunica albuginea is a dense layer of connective tissue that surrounds the testes.
- It is not specifically associated with the outer coat of seminiferous tubules.
In conclusion, the correct answer is A: Tunica propria, as it is the fibrous connective tissue layer that forms the outer coat of the seminiferous tubules.

At the time of sexual excitation, muscles in penis are relaxed.
The muscles in the penis play a crucial role in sexual arousal and functioning. When a person becomes sexually aroused, the muscles in the penis undergo certain changes to facilitate an erection. Here is a detailed explanation of what happens to the muscles in the penis during sexual excitation:
1. Smooth Muscles Relaxation:
- Smooth muscles in the walls of blood vessels and cavernous bodies of the penis relax.
- This relaxation is primarily mediated by the release of nitric oxide (NO) in response to sexual stimulation.
- Nitric oxide causes the smooth muscles to relax, leading to vasodilation and increased blood flow to the penis.
2. Corpus Cavernosum Expansion:
- The relaxation of smooth muscles allows the cavernous bodies (corpora cavernosa) of the penis to expand and fill with blood.
- As the cavernous bodies fill with blood, they become engorged and rigid, resulting in an erection.
- The expansion of the corpus cavernosum is essential for maintaining the rigidity of the penis during sexual activity.
3. Corpus Spongiosum Relaxation:
- The corpus spongiosum is another erectile tissue in the penis that surrounds the urethra.
- During sexual excitation, the smooth muscles in the corpus spongiosum also relax.
- This relaxation allows the corpus spongiosum to fill with blood, helping to maintain the rigidity of the penis and ensure the uninterrupted flow of semen through the urethra during ejaculation.
In summary, the muscles in the penis are relaxed during sexual excitation. This relaxation allows for increased blood flow to the penis, leading to an erection and facilitating sexual intercourse.

Answer:
The acid that occurs in semen is citric acid. Here is a detailed explanation:
Citric acid:
- Citric acid is a weak organic acid that is found in various fruits and vegetables, including citrus fruits like lemons and oranges.
- It is also present in the seminal fluid, which is a component of semen.
- Citric acid is produced by the prostate gland and is secreted into the seminal fluid.
- Its main function in semen is to provide energy for the sperm cells.
- Citric acid acts as a substrate for the enzyme ATP citrate lyase, which converts citric acid into acetyl-CoA, a molecule that can be used by the sperm cells for energy production.
- Therefore, citric acid plays a crucial role in sperm function and fertility.
In summary, citric acid is the acid that occurs in semen.

Secretion of which gland has high percentage of fructose:


There are several glands involved in the production of seminal fluid, which is the fluid that carries sperm during ejaculation. The secretion of which gland has a high percentage of fructose can be determined by analyzing the composition of seminal fluid.
The glands involved in the production of seminal fluid are:
- Prostate gland
- Cowper's gland (bulbourethral gland)
- Seminal vesicle
- Tyson's gland
Analysis:
To determine which gland has a high percentage of fructose, we need to consider the composition of seminal fluid.
- Prostate gland: The prostate gland contributes to the production of seminal fluid, but it does not contain a significant amount of fructose.
- Cowper's gland: The Cowper's gland, also known as the bulbourethral gland, produces a small amount of pre-ejaculatory fluid, but it does not contribute a significant amount of fructose to the seminal fluid.
- Tyson's gland: Tyson's gland is a small sebaceous gland located near the frenulum of the foreskin. It does not play a role in the production of seminal fluid and does not contribute fructose.
- Seminal vesicle: The seminal vesicles are the main glands responsible for producing the majority of seminal fluid. They contribute around 60-70% of the volume of seminal fluid and are known to contain a high percentage of fructose. The fructose in seminal fluid provides energy for sperm motility.
Conclusion:
Based on the analysis, the gland that has a high percentage of fructose in its secretion is the seminal vesicle.

Explanation:
If the testes of a male rabbit are not transferred from the abdominal cavity to the testes sac, it will lead to the following consequences:
1. Sperms will not form: The main function of the testes is to produce sperm cells through a process called spermatogenesis. If the testes remain in the abdominal cavity, they will not be able to undergo the necessary temperature regulation required for sperm production. As a result, sperms will not be formed.
2. Absence of male characters: The transfer of testes from the abdominal cavity to the testes sac is necessary for the development of male reproductive characteristics. Without this transfer, the male rabbit will not develop traits such as the growth of the penis, scrotum, and other secondary sexual characteristics.
It is important to note that the other options mentioned in the question, such as the death of the rabbit or the absence of male reproductive system development, are not accurate consequences of this specific scenario. The absence of testes in the scrotum may have other implications, but it would not directly lead to the death of the rabbit or the complete absence of the male reproductive system.

Explanation:
The uterus masculinus in mammals refers to a structure that is present in male animals. It is derived from the Mullerian duct, which is a structure that develops during embryonic development in both males and females. Here is a detailed explanation of each option:
A) Inguinal canal:
- The inguinal canal is a passage in the abdominal wall that allows the descent of the testes into the scrotum.
- It does not give rise to the uterus masculinus.
B) Wolffian's duct:
- The Wolffian's duct is a precursor to the male reproductive tract, including the epididymis, vas deferens, and seminal vesicles.
- It does not give rise to the uterus masculinus.
C) Mullerian duct:
- The Mullerian duct is a structure that forms during embryonic development in both males and females.
- In females, the Mullerian duct develops into the uterus, fallopian tubes, and upper part of the vagina.
- In males, the Mullerian duct regresses due to the presence of anti-Mullerian hormone (AMH) secreted by the testes. However, remnants of the Mullerian duct can persist in the male reproductive system as the uterus masculinus.
D) Ejaculatory duct:
- The ejaculatory duct is a structure formed by the union of the vas deferens and the duct of the seminal vesicle.
- It does not give rise to the uterus masculinus.
Therefore, the correct answer is C) Mullerian duct, as the uterus masculinus in mammals is derived from the Mullerian duct.

Explanation:
The correct answer is C: Cryptorchidism.
Cryptorchidism refers to the failure of the testes to descend into the scrotum. It is a common condition that occurs in mammals, including humans.
Key Points:
- Cryptorchidism is a medical term used to describe undescended testes.
- The testes are normally formed in the abdomen during fetal development and gradually descend into the scrotum before birth.
- In cases of cryptorchidism, one or both testes fail to descend into the scrotum.
- This condition can occur due to various factors, including hormonal imbalances, genetic factors, and anatomical abnormalities.
- Cryptorchidism is more common in premature infants, but it can also occur in full-term infants and older children.
- If left untreated, cryptorchidism can lead to complications such as infertility, testicular cancer, and torsion (twisting) of the testes.
- Treatment for cryptorchidism typically involves surgical intervention to bring the undescended testes into the scrotum.
- Early diagnosis and treatment are important to prevent long-term complications and improve fertility outcomes.
Conclusion:
Failure of the testes to descend into the scrotum is known as cryptorchidism. It is a common condition that can occur in mammals, including humans. Early diagnosis and treatment are important to prevent complications and improve fertility outcomes.

Clupein Protein Occurrence
Introduction:
Clupein protein is a specific protein that occurs in certain reproductive cells. Let's explore where it can be found.
Answer:
The occurrence of Clupein protein can be observed in:
A: Human Sperms:
- Clupein protein is present in human sperm cells.
- It plays a crucial role in the structure and function of sperm.
B: Avian Sperms:
- Clupein protein is also found in avian (bird) sperm cells.
- Similar to human sperm, it contributes to the structure and function of avian sperm.
C: Human Ova:
- However, Clupein protein is not present in human ova (eggs).
- It is primarily associated with sperm cells rather than ova.
D: All the Above:
- Based on the given options, the correct answer is A (Human sperms).
- Clupein protein occurs in human sperms but not in human ova.
Therefore, Clupein protein is found in human and avian sperm cells but not in human ova.

Partitions of testis develop from:
The partitions of the testis develop from the Tunica albuginea.
Explanation:
The testis is the male reproductive organ responsible for producing sperm and testosterone. It is composed of different structures, including the tunica albuginea, tunica vasculosa, tunica vaginalis, and rete testis.
The partitions of the testis, also known as septa, are fibrous connective tissue structures that divide the testis into lobules. These partitions play a crucial role in supporting and protecting the testis, as well as providing a framework for the production and storage of sperm.
Here is a breakdown of the development of testis partitions:
1. Tunica albuginea: The tunica albuginea is a dense fibrous capsule that surrounds the testis. During development, it gives rise to the partitions or septa that divide the testis into compartments called lobules. These septa extend from the tunica albuginea into the testis, creating separate spaces for each lobule.
2. Tunica vasculosa: The tunica vasculosa, also known as the vascular layer, is a network of blood vessels that supply nutrients to the testis. It does not directly contribute to the development of the partitions.
3. Tunica vaginalis: The tunica vaginalis is a serous membrane that covers the testis. It does not play a role in the development of the partitions.
4. Rete testis: The rete testis is a network of tubules located at the mediastinum testis, the central region of the testis. It serves as a collecting system for sperm and does not contribute to the development of the partitions.
In summary, the partitions of the testis develop from the tunica albuginea, which gives rise to septa that divide the testis into lobules. These partitions are essential for the organization and function of the testis.

The vas deferens is a long, muscular tube that carries sperm from the epididymis to the ejaculatory ducts in males. It plays a crucial role in the transport of sperm during ejaculation.
The vas deferens arises from the cauda epididymis, which is the lower portion of the epididymis. The epididymis is a coiled tube located on the testicle that stores and matures sperm.
Here is a detailed explanation of the options:
A. Cauda-epididymis: This is the correct answer. The vas deferens arises from the cauda epididymis.
B. Caput epididymis: The caput epididymis is the head of the epididymis, but the vas deferens does not arise from here.
C. Corpus epididymis: The corpus epididymis is the body of the epididymis, but the vas deferens does not arise from here.
D. Rete testis: The rete testis is a network of tubules located within the testicle, but the vas deferens does not arise from here.
In conclusion, the vas deferens arises from the cauda epididymis.

The common duct formed by the union of vas-deferens and duct from seminal vesicle is the ejaculatory duct.
The ejaculatory duct is an important structure in the male reproductive system that is responsible for transporting semen. Here is a detailed explanation of the common duct and its formation:
1. Vas-deferens: The vas-deferens, also known as the ductus deferens, is a long, muscular tube that connects the epididymis to the ejaculatory duct. It carries sperm from the testes to the urethra.
2. Seminal vesicle: The seminal vesicle is a gland located behind the bladder that produces seminal fluid. This fluid contains various substances that nourish and protect the sperm.
3. Formation of the ejaculatory duct: The vas-deferens and the duct from the seminal vesicle join together to form the ejaculatory duct. The union occurs in the prostate gland, which is a walnut-sized gland located below the bladder and in front of the rectum.
4. Location and function of the ejaculatory duct: The ejaculatory duct passes through the prostate gland and opens into the urethra. It plays a crucial role in the ejaculation process by propelling sperm and seminal fluid into the urethra, from where it can be expelled from the body during sexual intercourse.
In conclusion, the common duct formed by the union of the vas-deferens and duct from the seminal vesicle is the ejaculatory duct. It serves as a conduit for the transport of sperm and seminal fluid during ejaculation.

Statement A: Spermatogenesis is the formation of sperm cells.
- Spermatogenesis is the process by which sperm cells are produced in the testes of male animals.
- It involves the differentiation of spermatogonia (germ cells) into sperm cells through a series of mitotic and meiotic divisions.
- This process occurs within the seminiferous tubules of the testes.
Statement B: Spermatogenesis occurs in the seminiferous tubules.
- The seminiferous tubules are the functional units of the testes where spermatogenesis takes place.
- These tubules are lined with specialized cells called Sertoli cells, which support and nourish the developing sperm cells.
- Spermatogenesis involves the sequential development of spermatogonia, spermatocytes, spermatids, and finally mature sperm cells.
Statement C: Follicle-stimulating hormone (FSH) indirectly stimulates spermatogenesis.
- FSH is a hormone released by the pituitary gland in response to signals from the hypothalamus.
- In males, FSH acts on the Sertoli cells within the seminiferous tubules, stimulating them to produce and release various factors that are necessary for spermatogenesis.
- These factors include androgen-binding proteins, inhibin, and various growth factors that support the development and maturation of sperm cells.
Statement D: All of these are correct.
- Both statement A and B are correct as spermatogenesis is the formation of sperm cells, and it occurs in the seminiferous tubules.
- Statement C is also correct as FSH indirectly stimulates spermatogenesis through its actions on the Sertoli cells.
Therefore, the correct answer is D. All of these statements are correct.

Scrotum communicates with abdominal cavity through the inguinal canal

The scrotum is a pouch of skin that contains the testes (male reproductive organs) along with other structures such as blood vessels, nerves, and the spermatic cord. The scrotum is located outside the abdominal cavity but is connected to it through the inguinal canal. The inguinal canal is a passage that extends from the abdominal cavity to the scrotum. It allows structures such as blood vessels, nerves, and the spermatic cord to pass through.

Key points:

• The scrotum is a pouch of skin that contains the testes.


• The inguinal canal is a passage that connects the abdominal cavity with the scrotum.


• The inguinal canal allows structures such as blood vessels, nerves, and the spermatic cord to pass through.

In conclusion, the correct answer is B. Inguinal canal.

Tunica albuginea is the covering around the:
- Testis: The correct answer is B. The tunica albuginea is a dense fibrous capsule that surrounds each testis. It provides structural support and protection to the testis.
- Oviduct: The tunica albuginea is not found around the oviduct. The oviduct, also known as the fallopian tube, is a part of the female reproductive system and does not have a tunica albuginea.
- Kidney: The tunica albuginea is not present around the kidney. The kidney is covered by a fibrous capsule called the renal capsule, not the tunica albuginea.
- Heart: The tunica albuginea is not found around the heart. The heart is covered by a double-layered membrane called the pericardium, not the tunica albuginea.
In summary, the tunica albuginea is the covering around the testis. It provides support and protection to the testis.

Testosterone is secreted by Leydigs cells
Testosterone is a hormonal steroid that is primarily produced in the testicles of males. It plays a crucial role in the development and maintenance of male reproductive tissues and characteristics. The secretion of testosterone is regulated by a complex control system involving several organs and cells in the body.
Leydigs cells
- Leydigs cells, also known as interstitial cells, are located in the connective tissue surrounding the seminiferous tubules in the testes.
- These cells are responsible for the synthesis and secretion of testosterone.
- Leydigs cells respond to luteinizing hormone (LH) secreted by the pituitary gland, which stimulates the production of testosterone.
- LH binds to receptors on Leydigs cells, initiating a cascade of biochemical reactions that result in the production and release of testosterone.
Other cells and organs involved in testosterone production
- Sertoli cells: These cells are located within the seminiferous tubules and play a crucial role in supporting the development of sperm cells. While Sertoli cells do not directly secrete testosterone, they provide the necessary environment for Leydigs cells to produce testosterone.
- Pituitary gland: The pituitary gland, located at the base of the brain, releases luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH stimulates Leydigs cells to produce testosterone, while FSH acts on Sertoli cells to support sperm production.
Key Takeaways
- Testosterone is primarily secreted by Leydigs cells in the testes.
- Leydigs cells respond to luteinizing hormone (LH) secreted by the pituitary gland.
- Other cells involved in testosterone production include Sertoli cells and the pituitary gland.

Penile Urethra Traverses through Corpus Spongiosum
The penile urethra is the tube that carries urine and semen through the penis. It passes through different structures in the penis, including the corpora cavernosa and the corpus spongiosum. However, it specifically traverses through the corpus spongiosum.
Here is a detailed explanation of why the answer is B – Corpus Spongiosum:
- Corpora cavernosa: These are two chambers of erectile tissue that run along the upper side of the penis. They are responsible for the rigidity and erection of the penis but do not contain the penile urethra.
- Corpus callosum: The corpus callosum is a structure in the brain that connects the left and right cerebral hemispheres. It is not located in the penis and is not involved in the passage of the penile urethra.
- Corpus striatum: The corpus striatum is a part of the basal ganglia in the brain and is not related to the penile urethra.
- Corpus spongiosum: This is a column of erectile tissue that surrounds the penile urethra. It extends from the base of the penis to the glans (head) of the penis. The penile urethra traverses through the corpus spongiosum, allowing the passage of urine and semen during ejaculation.
In summary, the penile urethra passes through the corpus spongiosum, which is a column of erectile tissue that surrounds it. This arrangement ensures proper functioning and the passage of urine and semen through the penis.

The seminiferous tubules are the functional units of the testes, responsible for the production of sperm. They are composed of several layers of cells that play different roles in the process of spermatogenesis. The correct answer to the given question is D: Germinal epithelium.
Here is a detailed explanation of the components of the seminiferous tubules:
1. Germinal epithelium:
- The innermost layer of cells in the seminiferous tubules.
- Composed of spermatogonia, which are the stem cells that give rise to sperm cells.
- These cells undergo mitosis to produce primary spermatocytes, which then undergo meiosis to produce spermatids.
2. Spermatogonia:
- Stem cells located in the germinal epithelium.
- Divide by mitosis to maintain the population of spermatogonia and produce primary spermatocytes.
3. Spermatocytes:
- Derived from spermatogonia.
- They undergo meiosis to produce haploid spermatids.
4. Spermatids:
- Derived from spermatocytes.
- These immature cells undergo a process called spermiogenesis to differentiate into spermatozoa or sperm cells.
5. Sertoli cells:
- Found in between the germinal epithelium cells.
- Provide physical support to developing sperm cells.
- Produce nutrients and hormones essential for sperm development.
6. Leydig cells:
- Located outside the seminiferous tubules.
- Produce testosterone, a hormone necessary for the development and maturation of sperm cells.
In summary, the seminiferous tubules are composed of germinal epithelium, which includes spermatogonia, spermatocytes, and spermatids. The other supporting cells, such as Sertoli cells and Leydig cells, also play important roles in the process of spermatogenesis.

Sustentacular cells are found in the testis of mammals.
Here is a detailed explanation:
What are sustentacular cells?
- Sustentacular cells, also known as Sertoli cells, are specialized cells found in the testis of mammals.
- They are named after the Italian physiologist Enrico Sertoli, who first described them in 1865.
Functions of sustentacular cells:
- Sustentacular cells have multiple important functions in the testis, including:
- Providing physical support and protection to developing spermatogenic cells.
- Creating a blood-testis barrier to isolate the developing sperm cells from the immune system.
- Regulating the microenvironment within the seminiferous tubules, which is crucial for spermatogenesis.
- Secreting various growth factors and hormones that are necessary for the development and maturation of sperm cells.
- Phagocytosing and removing damaged or excess germ cells.
- Producing androgen-binding protein (ABP), which binds to testosterone and helps maintain high levels of testosterone in the seminiferous tubules.
Why are sustentacular cells important?
- Sustentacular cells play a vital role in the process of spermatogenesis, which is the production of sperm cells.
- They create a suitable environment for the development and maturation of sperm cells.
- They provide physical support and protection to the developing sperm cells.
- They regulate the hormonal and nutrient supply to the developing sperm cells.
- They help in the removal of damaged or excess germ cells.
- They contribute to the maintenance of high levels of testosterone, which is essential for spermatogenesis.
In conclusion, sustentacular cells are found in the testis of mammals and are crucial for the process of spermatogenesis. They provide physical support, regulate the microenvironment, secrete hormones and growth factors, and contribute to the development and maturation of sperm cells.

The bundles of muscles in the penis are:
1. Corpus cavernosa: This is a pair of erectile tissues that run along the length of the penis. It is responsible for the majority of the penis's rigidity during an erection. The corpus cavernosa contains smooth muscle fibers and is surrounded by tough fibrous tissue.
2. Corpus spongiosum: This is another erectile tissue that surrounds the urethra, which is the tube that carries urine and semen out of the body. The corpus spongiosum helps to maintain the shape and structure of the penis during an erection. It also contains smooth muscle fibers.
Explanation:
- The penis is composed of several structures, including erectile tissues and muscles.
- The erectile tissues, known as corpus cavernosa and corpus spongiosum, play a crucial role in achieving and maintaining an erection.
- The corpus cavernosa is located on the top side of the penis, while the corpus spongiosum surrounds the urethra and is located on the underside of the penis.
- Both the corpus cavernosa and corpus spongiosum contain smooth muscle fibers, which allow them to expand and fill with blood during an erection.
- The contraction and relaxation of these smooth muscle fibers are controlled by the autonomic nervous system.
- When the penis is not erect, the smooth muscle fibers are contracted, restricting blood flow to the erectile tissues.
- During sexual arousal, signals from the brain trigger the relaxation of the smooth muscles, allowing blood to flow into the corpus cavernosa and corpus spongiosum.
- This increased blood flow causes the erectile tissues to expand and become rigid, resulting in an erection.
- The bundles of muscles in the penis work together to facilitate sexual function and allow for a healthy erection.

Glans penis is covered by the prepuce.

The prepuce, also known as the foreskin, is a retractable fold of skin that covers the glans penis, which is the sensitive tip of the penis. It is present in males who are uncircumcised.

Functions of the prepuce:

• The prepuce protects the glans penis from friction and abrasion, keeping it moist and sensitive.


• It contains numerous nerve endings, which contribute to sexual pleasure and sensitivity.


• The prepuce plays a role in sexual intercourse by providing a gliding action and reducing friction between the penis and the vaginal walls.


• It acts as a natural lubricant during sexual activity.

Circumcision:

In some cultures or for medical reasons, circumcision may be performed, which involves the surgical removal of the prepuce. This exposes the glans penis permanently.

It is important to note that the glans penis is not covered by the prepuce in males who have undergone circumcision.

Lutein cells are found in the Corpus luteum.
The Corpus luteum is a temporary endocrine structure that forms after ovulation in the ovary. It develops from the ruptured ovarian follicle and plays a crucial role in the reproductive cycle. Lutein cells are specialized cells found within the Corpus luteum that produce and secrete hormones.
The presence of lutein cells in the Corpus luteum is essential for the production of progesterone, a hormone that is necessary for the maintenance of pregnancy. These cells also produce other hormones such as estrogen and inhibin.
The Corpus luteum undergoes a series of changes during the menstrual cycle. Initially, it is filled with granulosa cells and is called the Corpus luteum of the follicle. As the cycle progresses, it becomes the Corpus luteum proper, consisting mainly of lutein cells. If pregnancy does not occur, the Corpus luteum degenerates and forms the Corpus albicans.
In summary, lutein cells are found in the Corpus luteum, which is an important structure in the ovary involved in hormone production and the reproductive cycle.

Testis Location in Different Animals


Here is a detailed explanation of the location of testis in different animals:
Elephant:
- The testis in an elephant are abdominal in location.
- This means that they are situated inside the abdominal cavity of the elephant.
Shrew:
- The testis in a shrew are also abdominal in location.
- Similar to the elephant, they are situated inside the abdominal cavity of the shrew.
Both (1) & (2):
- Both elephants and shrews have abdominal testis, so option C is correct.
- This means that the testis in both these animals are located within the abdominal cavity.
None:
- This option is incorrect as both elephants and shrews have abdominal testis.
- Therefore, the correct answer is option C.
In summary, elephants and shrews have abdominal testis, which means that the testis in these animals are located inside the abdominal cavity.

Number of prostate glands in rabbits:
- The correct answer is A: One.
- Rabbits have a single prostate gland.
- The prostate gland is a part of the male reproductive system.
- It is located near the bladder and surrounds the urethra.
- The prostate gland produces seminal fluid, which helps nourish and transport sperm.
- The size and shape of the prostate gland can vary among different animal species.
- In rabbits, the prostate gland is relatively small compared to other mammals.
- The function of the prostate gland in rabbits is similar to that in other animals, including humans.
- It plays a role in reproductive processes and the production of seminal fluid.
- Understanding the anatomy and physiology of the prostate gland is important for studying reproductive health and fertility in rabbits.
- The presence of a single prostate gland in rabbits distinguishes them from animals with multiple prostate glands, such as dogs or humans.
- This anatomical difference is significant when considering the reproductive biology and behavior of rabbits.

The scrotal sacs of man and rabbit are connected with the abdominal cavity by the inguinal canal. Here is a detailed explanation:
Inguinal Canal:
- The inguinal canal is a passage in the anterior abdominal wall that connects the scrotal sacs in males and the labia majora in females to the abdominal cavity.
- It is located in the lower part of the abdomen, near the groin area.
- The inguinal canal is formed by the layers of abdominal muscles and is lined with connective tissue.
- In males, the inguinal canal contains the spermatic cord, which consists of blood vessels, nerves, and the vas deferens.
- In females, the inguinal canal contains the round ligament of the uterus.
Other options:
- Haversian canal: This canal is found in bones and is responsible for housing blood vessels and nerves.
- Vagina cavity: The vagina is a part of the female reproductive system and is not connected to the scrotal sacs.
- Spermatic canal: There is no specific anatomical structure called the spermatic canal. It is likely a misnomer or a term used in a different context.
Therefore, the correct answer is A: Inguinal canal.

Cryptorchidism: A Detailed Explanation

• Definition: Cryptorchidism refers to a condition in which one or both testes fail to descend into the scrotal sacs.


• Possible Causes: The exact cause of cryptorchidism is unknown, but it may be associated with hormonal abnormalities, genetic factors, or maternal factors such as smoking during pregnancy.


• Signs and Symptoms: The main sign of cryptorchidism is the absence of one or both testes in the scrotal sacs. Other symptoms may include a smaller scrotum, inguinal hernia, or a retractile testis that can move between the scrotum and groin.


• Diagnosis: Cryptorchidism is typically diagnosed during a physical examination. Imaging tests such as ultrasound or MRI may be performed to locate the undescended testes.


• Complications: If left untreated, cryptorchidism can lead to complications such as infertility, testicular cancer, and inguinal hernia.


• Treatment: Treatment options for cryptorchidism include hormone therapy, surgery, or a combination of both. Hormone therapy involves the administration of hormones to stimulate testicular descent. Surgery, known as orchiopexy, is performed to bring the undescended testes into the scrotal sacs.


• Answer: The correct answer is A - Unable to descend in scrotal sacs.

Cryptorchidism is a condition in which one or both testes fail to descend into the scrotal sacs. It is not related to the inability to produce sperms, having the testes surgically removed, or the testes remaining undeveloped. The condition can be diagnosed through a physical examination and additional imaging tests. If left untreated, cryptorchidism can lead to complications such as infertility, testicular cancer, and inguinal hernia. Treatment options include hormone therapy and surgery, with orchiopexy being the surgical procedure to bring the undescended testes into the scrotal sacs.

Explanation:
The testes occur in scrotal sacs outside the viscera in mammals due to the requirement of low temperature for spermatogenesis.
Reasons for this adaptation:
- Spermatogenesis, the process of sperm production, requires a temperature that is lower than the normal body temperature.
- The scrotal sacs provide an external environment for the testes, ensuring a lower temperature than the internal body temperature.
- The scrotum allows the testes to be positioned away from the warmth of the abdominal cavity, helping to maintain a cooler temperature.
- The cooler temperature in the scrotal sacs is essential for the proper development and maturation of sperm cells.
Other options:
- Presence of urinary bladder: The presence of urinary bladder does not play a direct role in the positioning of the testes in scrotal sacs.
- Presence of rectum: The presence of the rectum does not directly affect the positioning of the testes in scrotal sacs.
- Long vas-deferens: The length of the vas deferens does not determine the position of the testes in scrotal sacs.
Hence, the correct answer is option D: Requirement of low temperature for spermatogenesis.

Explanation:
The correct answer is B: Sertoli cells.
Spermatogonia are germ cells that undergo mitotic divisions to produce primary spermatocytes. In between spermatogonia, Sertoli cells are found. Sertoli cells are a type of supporting cell in the seminiferous tubules of the testes.
Here is a detailed explanation:
- Spermatogonia: These are the germ cells found in the testes responsible for producing sperm. They undergo mitotic divisions to produce primary spermatocytes.
- Sertoli cells: These are specialized cells found within the seminiferous tubules of the testes. They provide support and nourishment to developing sperm cells. They also play a crucial role in the process of spermatogenesis, including the regulation of hormone production and the formation of the blood-testis barrier.
- Epithelial cells: Epithelial cells are a type of cell that lines the surfaces of organs and body cavities. While they are found in the testes, they are not specifically located in between spermatogonia.
- Lymph space: Lymph spaces are small channels within tissues that allow for the movement of lymph fluid. They are not directly related to spermatogonia or Sertoli cells.
Therefore, the correct answer is B: Sertoli cells.

Sertoli cells are found in the testis of mammals.
Explanation:
Sertoli cells are a type of supporting cells found in the seminiferous tubules of the testis in mammals. These cells play a crucial role in the development and maturation of sperm cells. Here are some key points to explain why Sertoli cells are found in the testis of mammals:
- Sertoli cells provide structural support to the developing germ cells (spermatocytes and spermatids) within the seminiferous tubules.
- They form tight junctions with neighboring Sertoli cells, creating a blood-testis barrier that separates the developing germ cells from the blood circulation.
- Sertoli cells secrete various factors and hormones that are essential for spermatogenesis, the process of sperm production.
- They also regulate the microenvironment within the seminiferous tubules, maintaining optimal conditions for sperm development.
- Sertoli cells are involved in the phagocytosis of residual bodies, which are structures shed by developing sperm cells during maturation.
- They secrete androgen-binding protein (ABP), which helps in the concentration of testosterone within the seminiferous tubules.
- Sertoli cells also play a role in the release of mature spermatozoa into the lumen of the tubules.
Overall, Sertoli cells are an integral part of the testis in mammals and are vital for the process of spermatogenesis and the production of functional sperm cells.

The accessory genital gland that occurs only in male mammals is the prostate gland.
Explanation:
The male reproductive system in mammals consists of various organs and glands that are involved in the production, storage, and release of sperm. One of these glands is the prostate gland, which is found only in male mammals.
The prostate gland is a small, walnut-sized gland that is located below the urinary bladder and surrounds the urethra, the tube that carries urine and semen out of the body. It is responsible for producing and secreting a fluid that makes up a significant portion of semen. This fluid helps to nourish and protect the sperm as they travel through the reproductive tract.
The prostate gland is particularly important for the reproductive function of male mammals. It plays a crucial role in the process of ejaculation by releasing its fluid into the urethra during sexual arousal. This fluid mixes with sperm from the testes and secretions from other glands to form semen, which is then expelled from the body during ejaculation.
In summary, the prostate gland is an accessory genital gland that occurs only in male mammals. It plays a vital role in the reproductive system by producing and secreting a fluid that is essential for the function and survival of sperm.

Seminiferous tubule acts as the functional unit of the testis which opens into the vasa efferentia through rete testis. The vasa efferentia leave the testis and open into epididymis located along the posterior surface of each testis. The epididymis continues to vas deferens, that ascends to the abdomen and loops to pass over urinary bladder. It receives a duct from seminal vesicle and opens into the urethra as the ejaculatory duct. Each ejaculatory duct is formed by the union of the vas deferens with the duct of the seminal vesicle. They pass through the prostate and open into the urethra at the colliculus seminalis. These ducts store and transport the sperms from the testis to the outside through urethra.