ACCESSORY REPRODUCTIVE GLANDS
The substances secreted by the accessory reproductive glands help in reproduction, these are:
1. Seminal vesicle: It is also called Uterus-masculinus. It is formed from the Mullerian-duct of the embryo. In females, these ducts form the oviducts. Internally, it is lined by glandular epithelium which secretes seminal fluid, which is lubricating, transparent & jelly like substance, which makes 60–70% part of semen. It is slightly alkaline (pH 7.3). Fructose is found in seminal fluid, it acts as a fuel to the sperm. Fibrinogen, prostaglandin, citrate, inositol and several proteins are also present in semen.
2. Prostate gland: This gland is located below the urinary bladder. It is unpaired & made up of 5 lobes in man. In Rabbit 3 or 4 lobe are found. Each lobe opens into prostatic urethra through many fine apertures. It secretes slightly alkaline prostatic fluid which is milky, thick, sticky or jelly like. It makes about 30% part of semen and helps in sperm activation.
In the secretion of prostate - gland - Citric acid, Calcium, Phosphate, clotting enzyme and Profibrinolysin are present. The secretion of the prostate gland combines with the secretion of seminal vesicle and so the semen gets coagulated. In the coagulated semen, the mobility of sperms is reduced and so their energy is conserved.
After some time due to fibrinolysins, semen again liquefies and in this semen now the sperms can move.
(i) Enlargement of prostate results in prostatitis, in which urination is difficult or impossible.
(ii) BPH (Benign Prostatic Hypertrophy) is a medical condition, which occurs due to the increase in size of the prostatic gland.
(iii) Untreated BPH may leads to the cancer of Prostate.
3. Cowper's glands: It is a pair of glands found on lateral side of urethra. It is also called as bulbourethral gland. It is situated in membranous part of urethra & opens into penile urethra. It secretes transparent, slimy, jelly like fluid. It is slightly alkaline (pH is 7.2). This destroys the acidity of the urethra and cleans it for the movement of sperms.
Fig: Cowper's Gland Representation
4. Perineal or Rectal glands: These are found both in male and female rabbits. Perineal gland is found around external genital organ & perineal region, while rectal glands are found around external genital organs & anus. During the breeding season, these glands secrete odoriferous liquid which has pheromones or Ectohormones in it. The pheromone develops sexual attraction between opposite sexes & also develops desire for copulation.
In man, Perineal or Rectal glands are absent.
The products of the testes (spermatozoa) and prostate gland, along with fluid from the seminal vesicle, are collectively know as semen. Release of spermatozoa from urethra is known as ejaculation.
1. Body of Penis:
2. Erection of Penis: Erection of penis is purely vascular phenomenon and is controlled by A.N.S. It occurs due to increase of blood supply, due to dilation of penile arteries causing enlargement and hardening of penis. during this time the muscles of crura are relaxed.
Fig: Transverse section through the body of the Penis
HISTOLOGY OF SEMINIFEROUS TUBULES
Outer surface of seminiferous tubules is composed of white fibrous connective tissues called as tunica propria.
While inner surface is of cuboidal germinal epithelium. This epithelium is made of spermatogenic cells which forms sperm by spermatogenesis. Some columnar cells are found in the layer of germinal epithelium called as sertoli cells. These provide nutrition to sperm, so they are also called as sustentacular or nurse cells (these occur in mammals).
OTHER FUNCTION OF SERTOLI CELLS
(i) They phagocyte the injured or dead sperm cells
(ii) They are the basis of blood testis barrier
(iii) Sertoli cells produce inhibin and anti mullerian hormone.
(iv) Sertoli cells can synthesize estrogen from testosterone.
Some endocrine cells are found between seminiferous tubules in intertubular space, these are called as interstitial or Leydig cells. These cells secrete testosterone. The testosterone from Leydig's cells enter the seminiferous tubules by diffusion under the effect of ABP & promotes spermatogenesis.
Fig: Histology of Testis
MALE REPRODUCTIVE HORMONES
Testosterone: Secreted by Leydig cells. It is essential for