Saturday, April 15, 2017

Frog: Male Reproductive System

Male reproductive system consists of two testes attached to kidneys, several vasa efferentia and two urinogeniteal ducts. Copulatory organs are absent.


1.Testes: A pair of testes are present. Each testis is an elongated or ovoid, light-yellow body attached to the antero-ventral surface of each kidney by a double fold of peritoneum, called mesorchium. Near the anterior end of testis arise several branched finger-like fat bodies which provide reserve food to nourish developing spermatozoa and during hibernation.
Histologically, each testis is a compact mass of much coiled seminiferous tubules which internally remains lined by epithelial cells called as primordial cells. These cells undergo the process of spermatogenesis to form sperms. The process of formation of sperms is called as spermatogenesis. In the space between these seminiferous tubules interstitial cells or Leydig's cells are present which are endocrine in nature and produce male sex hormone , testosterone which is responsible for the development of copulatory pad and vocal sacs.
Structure of sperm:
A mature sperm is microscopic, elongated about 0.03 mm long structure. It consists of acrosome, head, body and tail.

The acrosome is apical cap like structure and is modified form of lysosome which produces chemical lysine to dissolve egg membrane, Thus, function of acrosome is to penetrate wall of egg. The head is elongated round structure with nucleus of its own size. The body is main part and consists of cytoplasm and cell organells with spirally coiled mitochondria. The tail is cytoplasmic extension of body and it makes the sperm migratory.

2. Vasa efferentia: All the seminiferous tubules in a testis are connected to form 10 to 12 narrow tubes, the vasa efferentia. These leave from the inner margin of testis, run through mesorchium and enter the inner margin of kidney to open into the Bidder's canal. The Bidder's canal is vertical canal inside kidney and connected to the ureter through collecting tubules of kidney. Thus, vasa efferentia conduct mature spermatozoa from testis to the ureter of kidney.
3. Urino-genital duct: Ureter in male frog is both a urinary duct and vas deferens i.e. carries both urine and sperms, hence it is called as urino-genital duct. The ducts of both the sides run posteriorly and open into roof of cloaca separately on urinogential papillae. In some species of frog, the urinogential ducts are enlarged near kidneys  forming seminal vesicles for temporary storage of spermatozoa until needed.