Embryologie

Specific objectives:

Describe female contraceptive methods

Describe male contraceptive methods

Explain assisted reproductive technologies (ART)

A twin pregnancy is a type of multifetal gestation in which two fetuses develop simultaneously in the uterus. Two major types exist:

1-Dizygotic twins (fraternal twins)

2-Monozygotic twins (identical twins)

The stem Cells are undifferentiated or partially differentiated cells that can differentiate into various types of cells and proliferate indefinitely to produce more of the same stem cell, under certain conditions whether it be (natural or experimental).

Specific objectives:

1-Observe the stages of fertilization under a phase contrast microscope.

2-Describe the embryo of the first & second week of development on histological section.

-Modification of the maternal organism.

Introduction

The embryonic appendages are transitional organs that accompany the embryo and the fetus during its development and ensure its survival and vital functions: nutrition, respiration, excretion. These are non-embryonic tissues located between the fetus and the mother's uterus and which will be annexed to the embryo throughout intrauterine life. They will be eliminated at birth.

The embryonic appendages are represented by:

✓ The amnion : ( pl. : amnions) it is a membrane delimiting the amniotic cavity, in which the amniotic fluid is found, it lines the internal wall of the placenta.

✓ The yolk vesicle: it is at its wall that the angioforming islets will appear as well as the first sex cells "primordial gonocytes".

✓ The allantoid: participates in the formation of the umbilical cord.

✓ The umbilical cord: it connects the placenta to the fetus.

The fourth week of development is characterized by two major events:

1-               The delimitation of the embryo, which transforms the trilaminar embryonic disc into a tubular form via folding in both transverse and longitudinal directions.

2-               The beginning of organogenesis, marked by the appearance of organ primordia derived from each embryonic germ layer. The period of embryonic development extends until the eighth week, after which the primary external forms are recognizable.

Specific objectives:

1-Describe a cross section of the ovary.

2-Observed the dehiscence of the mature follicle and the fate of this follicle.

Introduction:

The ovaries have two interrelated functions: gametogenesis (the production of gametes: Developing gametes are called oocytes; mature gametes are called ova.) and steroidogenesis (the production of steroids: estrogens and progestogens). In women, the production of gametes is called oogenesis.

The third week of embryonic development is marked by several events:

1. In the mother:

Clinical and biological signs of pregnancy become apparent.

2. At the level of the embryonic disc:

Two main processes occur:

   • Gastrulation, which corresponds to the establishment of the third germ layer (the chordo-mesoblast).

   • Neurulation, which corresponds to the differentiation of the neural tube, the primordium of the central nervous system.

3. In the embryonic annexes:

The chorionic sphere undergoes transformation, and the first vascular-blood and sexual rudiments appear (undifferentiated structures of the reproductive system).

4. The events occurring during the third week prepare for the period of organogenesis, extending from the fourth to the eighth week, during which the major organ systems differentiate.

Specific objectives:

1.     Describe the structure of the spermatozoa.

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The Spermogram and the spermocytogram are still basic examinations for assessing the characteristics of the semen.

Oogenesis is the process whereby oogonia differentiate into mature oocytes.

spermatogenesis, the process of producing haploid male gametes.