the sperm histology

موضوع: the sperm histology الأحد أغسطس 28, 2011 1:51 pm

Stages and processes of embryogenesis
Process	Result	Place and tyme
Fertilization	Zygote (unicellular organism)	Fallopian tube ampula
Cleavage	Blastula (multicellular organism)	Fallopian tube 2^nd -4^th days and uterine cavity 5^th-7^th days
Gastrulation	Gastrula (bilayered organism)	7-14^th days, endometrium
Neurulation	Neurula (threelayered organism with nerve tube)	14^th -17^th days …
Histogenesis	Tissues
Organogenesis	Organs
Systemogenesis	Systems of organs

postnatal period

Postnatal
period occurs after the birth and includes infancy, childhood, puberty,
adolescence, adulthood.

Infancy includes the first year after the birth. Newborn is infant of 1 month or less.

Childhood is period from 13 month untill
puberty. During this period primary and secondary teeth are appeared.

Puberty is period from 12 to 15 years,
during which secondary sex characteristics are developing. Puberty end in female with the first menstrual cycle
and in male with first pollution.

Adolescence is the
period from about 11 to 19 years of age, during which rapid physical and sexual
maturation occurs. There are active ossification (bones formation), growth of
the body and organs.

Adulthood is the period of full growth and
maturity (18-21 years).

Spermatozoa

Spermatozoa – the male germ cells
were exactly described by Levenguk and his pupil Gamm in 1677. They are 60-70
mkm long and have a very specific shape: each spermatozoon has a head, neck,
body and tail.

The head of spermatozoon is of oval flattened shape.
It contains elongated nucleus with condensing chromatin. A small amount of
cytoplasm in the head makes a special shape with perforatorium- sharp top of
the spermatozoon head. It is the most suitable shape for passage forward due to
the moving of flagella. There are 23 chromosomes inside – 22 autosomes and the
last one – sex chromosome (x or y). Accordingly, there are two types of
spermatozoa: androspermia and gynecospermia. Nuclear envelope has no nuclear
pores.

There is a
special structure – acrosome – at the top
of spermatozoon head. This acrosomic cap, or galea capitis is a specifically changed Golgi apparatus,
which contains enzymes hyaluronidaze, trypsin-like, glucosidases and other.
Bilaminar acrosomal cap covers the anterior two-thirds of the nucleus.
Acrosomal enzymes facilitate spermatozoon penetration of the corona radiata and
zona pelucida in fertilization.

The neck
is narrow: it contains a funnel-shaped basal body and a spherical centriole.
The basal body is also called the connecting piece because it helps to
establish an intimate union between the head and remainder of the spematozoon.
Axial fiber (axonema) is the principal component of the body and tail. It
is composed of 9 pairs of peripheral microtubules and one central pair. The
axial filament begins just behind the centriole. It passes through the middle
piece and most of the tail. The middle piece is long cylinder (1x7 мm) with a
lot of mitochondria, which are helically wrapped around the axonemal complex
for energy supply of spermatozoon.

Sperm is a male seminal fluid (semen) – complex
mixture produced by testis, the seminal vesicles and prostate gland. 3-5 ml of semen contains 200- 300
million spermatozoa (20-200 mln/ml). 75 % of them are alive, 50 %
actively moving, 60-70 % have normal structure. Secretions derived from
the male accessory glands. There are some growing, maturing cells like
spermatocytes and spermatids and some epitheliocytes and leucocytes in the
sperm. The fluid of the sperm is presented with water and some organic and
mineral components. The chemical reaction of a sperm is alkaline, just in such
medium spermatozoa are most active.

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