Test: Gametogenesis & Menstrual Cycle

• We are very well aware with the male reproductive system where testes are the primary sex organs and located in an extra abdominal pouch of skin called scrotum.
• Each testes possess nearly 250 testicular lobules and each lobule has at least one to three seminiferous tubules where the spermatogenesis process takes place.
• As we know that spermatogenesis as the name suggests is the process of generation of sperms.
• Spermatogonia or the immature germ cells are present within the seminiferous tubules and these cells divide by mitosis and some of them enter Meiosis I to become primary spermatocytes and then they complete Meiosis I to become secondary spermatocytes.
• Secondary spermatocytes now undergo Meiosis II to become spermatids which will differentiate into spermatozoa or sperms and will be released into the lumen of tubules.
• In these tubules are present two types of cells one is Sertoli’s cells which will provide nutrition to the growing sperms and the Leydig cells which secretes Testosterone which helps in maintaining the reproductive tract.
• Testosterone is a male hormone that is responsible for the male reproductive system's maintenance.

Therefore, from the above explanation we can say that spermatogenesis is promoted by Testosterone.

Hence, the correct answer is (C).

Spermatogenesis​:

• Post-ovulatory phase is also known as the luteal phase. During this period, the follicle proper folds inward on itself and transforms into the corpus luteum which is a steroidogenic cluster of cells that produces estrogen and progesterone. The action of progesterone increases the basal body temperature. 

  So, the correct answer is "Progesterone level is high during the post-ovulatory phase of the menstrual cycle."

• Corona Radiata

  The outermost membranous cover of the ovum at ovulation is corona radiata. It is formed by follicular cells. Inner to corona radiata is zona pellucida, which is made up of three different glycoproteins secreted by the ovum itself.

  

• Menopause marks the end of a woman's fertility and the cease of the menstrual cycle.
• The ovaries stop producing hormones and in humans, the menstrual cycle ceases at around 50 years of age. 

1. Zygote is also diploid and fertilized ovum formed by fusion of male and female gametes.

2. Spermatogonia are the cells on the inside wall of seminiferous tubules and consist of 46 chromosomes.

3. The secondary oocyte is a haploid cell that develops from the primary oocyte during puberty. It is a haploid cell with 23 chromosomes.

4. Oogonia are also diploid and are formed in the fetal ovary.​

Given below is the figure of follicle:

Ovulation occurs when the level of hormones is as follows:
(a) Low concentration of progesterone.
(b) High concentration of LH.
(c) High concentration of FSH.
(d) High concentration of estrogens.

Hence, the correct option is (D).

• Primary and secondary spermatocytes are formed through the process of spermatocytogenesis. Primary spermatocytes are diploid (2N) cells. After meiosis I, two secondary spermatocytes are formed. Secondary spermatocytes are haploid (N) cells that contain half the number of chromosomes.
• During meiotic cell-cycle progression, unequal divisions take place, resulting in a large oocyte and two diminutive polar bodies. Both these polar bodies are haploid in nature.
• A secondary oocyte only undergoes the second meiotic cell division to form a haploid ovum if it is fertilized by a sperm. The one egg cell that results from meiosis contains most of the cytoplasm, nutrients, and organelles. It is a haploid in nature.

The presence of estradiol and progesterone in the luteal phase results in negative feedback on both FSH and LH secretion. Because of this negative feedback, the levels of FSH and LH are relatively low in the luteal phase. This inhibits FSH release and thus restricts follicular development during the luteal phase.

Spermiogenesis is transformation of spermatids into spermatozoa whereas spermiation is the release of the sperms from sertoli cells into the lumen of seminiferous tubule.

• LH is a Luteinizing hormone produced by the gonadotropic cells in the anterior pituitary gland.
• It plays an important role in puberty, menstruation, and fertility.
• It triggers ovulation and development of the corpus luteum.
• In male, LH triggers the secretion of androgen called testosterone from the Leydig cells.
• FSH is follicle-stimulating hormone produced by gonadotropic cells in the anterior pituitary gland.
• It helps in regulation of development, growth, pubertal maturation and reproductive processes of the body.
• It stimulates the Sertoli cells of the testicles and helps in spermatogenesis, production of sperm.
• During the follicular phase, the LH and FSH increase gradually.
• They stimulate follicular development and estrogen secretion by follicular cells.

Thus, the correct answer is 'LH and FSH decrease gradually during the follicular phase.'