Spermatogenesis Blastocyst

 

SHORT NOTES

mature ovum

blasto cyst

notochord

placenta

 A. Spermatogenesis:-

 It is the process of maturation of male gametes in the wall of seminiferous tubules.

 • It involves a series of changes in which spermatogonia convertes into spermatozoa.

 • Duration: 64–74 days.

Different steps of Spermatogenesis:-

The following are different steps of Spermatogenesis :-

 1. Spermatocytosis :-

 • It is the process of conversion of spermatognia to primary spermatocytes.

 • It takes 16 days

 2. Meiotic Divisions:-

 • process of conversion of primary spermatocytes to secondary spermatocytes and then spermatids.

 • It takes 24 days.

 3. Spermiogenesis:-

 • It is the process of metamorphosis of spermatids to spermatozoa .

 • it takes 24 days.

 • The process by which a spermatid gradually changes its shape to become a spermatozoon is called spermiogenesis

Diagram of mature sperm

 B. Mature Ovum

 C. Blastocyst:-

 The series of rapid mitotic divisions of the ovum result in the formation of a morula, and then a blastocyst.

The blastocyst is a fluid-filled hollow sphere, which consists of an inner cell mass at one pole, surrounded by a thin wall of trophoblast cells.

 • it occurs Between 4th and 5th day and 32–64 cells stage.

 • The cavity of the blastocyst is the blastocoele.

 • The side of the blastocyst to which the inner cell mass is attached is called the embryonic or animal pole, while the opposite side is the abembryonic pole.

 • The trophoblast in contact with embryonic pole known as polar trophoblast. and the rest of it lining the wall of balstocyst is known as mural trophoblast.

 D. NOTOCHORD

The notochord is a midline structure that develops in the region lying between the cranial end of the primitive streak and the caudal end of the prochordal plate.

 E. PLACENTA:-