Male reproductive system:

Internal male reproductive organs consists of

a) a pair of testis,

b) a pair of vasa deferens,

c) seminal vesicle

d) Ejaculatory duct

e) accessory glands i) mesodenia ii) ectodenia and

f) Genitalia

1. Testis:

• Size is same as ovaries of Apterygota and very much smaller in Pterygota.
• They lie in visceral cavity above the alimentary canal.
• Each testis consists of number of oval shaped structures known as follicles or sperm tubes.
• The entire follicle is covered by a peritoneal membrane whereas the testis is completely enveloped within a coat known as scrotum.

Structure of follicle

• The structure of follicle is divided into 4 regions. i.e.

(i) Germarium: It is the region containing primordial germ cells or spermatogonia which undergo multiplication. (Zone of spermatogonia).

(ii) Zone of growth: It is the area where spermatogonia increase in size, undergo repeated mitosis and develop in to spermatocytes. (Zone of spermatocytes).

(iii) Zone of division and reduction: It is the area where spermatocytes undergo meiosis and give rise to spermatids (Zone of spermatids).

(iv) Zone of transformation: It is the area where spermatids get transformed into spermatozoa. (Zone of spermatozoa).

2. Vasa deferens: These are the long tubes formed by the union of vasa efferens which receives the sperms from testis and allow their transport to the ejaculatory duct.

3. Seminal vesicles: Each vasa deferens become enlarged posteriorly to form a sac like structure called seminal vesicle for storage of spermatozoa for some time.

4. Ejaculatory duct: Both the vasa deferens of the two testis unite posteriorly to form a common median ejaculatory duct. The terminal section of ejaculatory duct is enclosed in a finger like evagination of body wall, male copulatory organ or aedeagus or penis.

5. Accessory glands: These are 1-3 pairs & open in to the ejaculatory duct. In most cases their secretion mix with spermatozoa. These glands are called mushroom glands in cockroaches and mantids because of their appearance as mushrooms. This secretions facilitates sperm transmission from male to female.