Identifying point of histological slide of skeletal muscle

Skeletal muscle : slide identification under microscope 

1.      Peripherally placed multiple nucleus 

2.      Shape of cells: long, cylindrical 

3.      No branching present 

Histological features of higher magnification: 

Cross striation present

Principles of teratology : lecture notes of embryology

Principles of Teratology: ( capacity of an agent to produce birth defects)

1. Susceptibility to teratogenesis depends on the genotype of the conceptus
2. Susceptibility to teratogens varies with the developmental stage at the time of exposure
3. Manifestations of abnormal development  depend on dose and duration of exposure to a teratogen
4. Teratogens act in specific ways on developing cells to initiate abnormal embryogenesis
5. Manifestations of abnormal development are death, malformation, growth retardation & functional disorders

Lecture notes on notochord in embryology

Define notochord: it is the primordial axis of the embryo around which the axial skeleton forms

Formation of notochord

1.      appearance of primitive streak

2.      the cranial end of primitive streak proliferates to form a primitive node

3.      primitive node form the notochordal process , which extends cranially from the primitive node between the embryonic ectoderm and endoderm

4.      a small depression  is developed in the primitive node called primitive pit which extends into the notochordal process and forms notochordal canal.

5.      the notochordal process extends from primitive node to the prechordal plate

6.      opening develop in the floor of the notochordal canal , and the remaining notochordal process flattened and form notochordal plate

7.       the notochordal plate in folds to form the notochord

Lecture notes on decidua in embryology

Decidua:

Definition : Deciduas means gravid endometrium

Decidua reaction:

 i) cells of the endometrium polyhedral and loaded with glycogen and  lipids

  ii) intercellular spaces are filled with extravasate

  iii) the tissues is edematous

At first it occur at the site of implantation but soon spread throughout the endometrium 

Parts of deciduas : it is divided into three parts

1.      decidua basalis : parts of decidua deep to the developing embryo which contributes to the development of placenta

2.      decidua capsularis : part of decidua which surround the embryo and it is separated from the uterine cavity

3.      decidua parietalis : rest of the decidua excluding decidua basalis and decidua capsularis 

Lecture notes on implantation

Implantation:

Definition: The process during which the blastocyst attaches to the endometrium and subsequently embeds in it.

It occurs at 6 days after fertilization and

by the 11 th to 12^th days of development the blastocyst is completely embedded in the endometrial stroma.

Bleeding may occur at the implantation site as a result of increase blood flow into the lacanar spaces.

 This bleeding occur near the 28^th day of menstrual cycle, it may confused with normal menstrual bleeding.

Q: In which phase of menstrual cycle implantation is occurred?

Ans: The secretory phase, during which time uterine glands and artery become coiled.

What are the phases of menstrual cycle?

1.      Menstrual phase

2.      proliferative(follicular)  phase

3.      secretory (progestational) phase

What is ovarian cycle?

It is a regular monthly cyclic changes in the ovaries (which start at puberty )

Phases are:

i)                    follicular development

ii)                  ii) LH surge (ovulation)

Normal sites of implantation: The blastocyst implants in the endometrium along the anterior or posterior wall of fundus of uterus. (Trophoblast cells of blastocyst invade the epithelium and underlying endometrial stroma with the help of proteolytic enzymes.)

Abnormal implantation:

1.      implantation in abdominal cavity

2.      implantation in the pouch  of Douglas

3.      implantation in the ampullary region of f. tube (most common)

4.      Implantation in the internal os

5.      Ovarian implantation

6.      Interstitial implantation

7.      Tubal implantation