Gametogenesis

Gametogenesis

Hi Viewers Today we will discuss about the first topic of Human Reproductive Physiology and that is Gametogenesis. Now let us dig out the meaning of Gametogeneis In the word Gamet/o/genesis. a) O is the combining vowel, which is joining two word roots gamete and genesis b)  Gamete means a mature haploid male or female germ cells, which when join it forms zygote c)  Genesis means production So, Production of gametes is known as Gametogenesis Gametogenesis It is the process of formation and differentiation of haploid gametes sperms and ova from the diploid primary germ cells gametogonia that are spermatogonia and oogonia present in primary sex organs called gonads, which are testes and ovary   Types Gametogenis is of two types spermatogenesis and oogenesis     SPERMATOGENSIS   It is the formation of haploid, microscopic and motile male gametes called spermatozoa from the diploid spermatogonia in the testes of male sex organ   Time period It is a continuous process and it is completed in about 74 days   Mechanism It has got two parts A.  Formation of spermatids and B.  Spermiogenesis   Formation...
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Implantation of Embryo in Human

Implantation of Embryo in Human

Hi viewers: Today we will discuss about the implantation of Embryo in Human Implantation of Embryo in Human Definition The process of attachment of blastocyst on the endometrium of the uterus is called implantation Period Though the implantation may occur at any period between 6th and 10th day after the fertilization but generally it occurs on seventh day after fertilization Mechanism of Implantation of embryo Early Development Cleavage and preimplantation events:  Fertilization of mammalian eggs, occurs in the oviduct, in human in the ampulla of fallopian tube.  Cleavage divisions proceeds slowly as the zygote moves slowly towards the uterus.  Cleavage are holoblastic and slightly unequal as a rule.  They are not synchronous and produce a loose ball of cells the morula within the intact zona pellucida.  The morula comprises 16 or  more cells by the time it reaches the uterus which occurs in 3 – 5 days in the human beings.  Once in the uterus the cells begin to divide rapidly and the embryo takes the form of a...
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Histology of Ovary

Histology of Ovary

Hi Viewers: Today we will discuss about the histology of Ovary.  The term hist/o/logy means a)  O is the combining vowel, which connects the word roots histo and logy b)  histo means tissue c)  logy means study So the histology of ovary means study of ovary Ovary The histological section comprises stroma and parenchyma The stroma is thin and represented by thick collagenous fibres The parenchyma represented by the ovarian follicles 3.  he ovarian follicles (early primary follicle, late primary follicle, antral follicle, mature Graafian follicle) are all in different stages of development 4.  A mature Graafian follicle comprises of following structures a) The follicle encloses in a spacious cavity  the antrum filled with watery fluid  the liquor folliculi b) The follicle is covered by theca interna and theca externa c)  At one core there is an aggregation of granulosa cells to form a stalk like structure holding the mature oocyte is called discus proligerus or cumulus oophorus d) The ovum has a distinct nucleus e) The ovum is surrounded by follicular cells called corona radiata 5)...
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Histology of Testis

Histology of Testis

Hi Viewers: Today we will discuss about the histology of Testis.  The term hist/o/logy means a)  O is the combining vowel, which connects the word roots histo and logy b)  histo means tissue c)  logy means study So the histology of testis means study of testis Testis The histological section comprises stroma and parenchyma The stroma is thin and represented by reticulin fibres of tunica albuginea The parenchyma represented by the sections of seminiferous tubules   The seminiferous tubules are of different shapes and size.  Within the seminiferous tubules following structures are found Attached to the thin basement membrane there are germinal epithelium layers of cells with cuboidal epithelial cells with prominent nuclei (Primary spermatogonia) There are triangular and truncated Sertoli cells.3.  Concentric layers of primary spermatocyte, secondary spermatocyte and spermatids are present.4.  At the centre of the lumen there are cluster of sperm with long flagellated tail5.  At the interstitious zone there are patches of Leydig cells presenting the endocrine part of the testes6.  Sections of blood vessel...
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The Structure of an Ovum

The Structure of an Ovum

The Structure of an Ovum An ovum female haploid gamete and is primarily concerned with receiving sperm and is determined to develop into a fully developed multicellular organism after fertilization.   Historical Aspect: Harvey in 1651 and DeGraaf in 1672 described the structure of gametes.   Barry was the first man to report the presence of sperm inside an egg in 1943.   Structure: A mature ovum is roughly spherical in shape with a central nucleus and a large volume of cytoplasm containing vacuoles and yolk granules. Within the nucleus, nucleolus and the nuclear reticulum are often conspicuous. Under EM, the oolemma is found to produce many microvilli. A juxtanuclear Golgi complex, rough ER with ribosomes and a number of mitochondria are also found. Zona pellucida is obserbed in an ovum. In mammalian egg, the oolemma is surrounded with corona radiata cells. In yolky eggs, the yolk free area is called the animal pole and the yolk ladden zone is known as the vegetal pole. In many...
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The Structure of Sperm

The Structure of Sperm

Hi viewers: Today we will discuss about the Structure of sperm. The Structure of Sperm   What is a spermatozoa? It is a haploid male gamete whose primary function is to fuse with ovum to restore diploidy and to transmit paternal characters to the offsprings.   A mammalian sperm is minute, microscopic, flagellated, and motile gamete with no nutritive material.   It has got four basic structures   Structure   Head Shape of head varies in different mammals.  It consists of Acrosome and Nucleus   Acrosome It is small structure present at the tip of nucleus.  It is formed from a part of Golgi body of spermatid, which contains a lytic enzyme called hyaluronidase.  During the sperm entry into the ovum or in other words during fertilization it helps the sperm penetration into the ovum.  The acrosome is covered by a fibrillary sheath called galea.   Nucleus It is generally long, narrow and pointed but it is oval in human.  It carries chromatin reticulum, which is the carrier of genetic information   Neck It is a smallest part of a sperm and it...
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The Menstrual Cycle

The Menstrual Cycle

Hi viewers: Today we will discuss about the menstrual cycle of female Homo in this blog. Menstrual Cycle Periodica discharge of blood along with other materials (including one unfertilized ovum) from the female genital tract is called menstruation. Regular repetition of events from one menstruation to the next is called menstrual cycle.  This uterine event is the most prominent change in the reproductive cycle of a female. Duration and flow: Menstrual bleeding is normally painless and contains no clot.  Periodically and duration of bleeding is very often remarkable constant in a particular woman, but highly variable in different woman.  The cycle is usually of 28 +/-4 days duration, duration of bleeding is 4 days and amount of bleeding is 4 to 40 ml.  If the bleeding is greater than 80 ml, it is taken as abnormal.  The blood is mainly arterial and contains shedded endometrium.  It is rich in prostaglandins and fibrnolysins.  The fibrinolysins prevent coagulation if the bleeding is normal, but fails to do...
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