Anatomy

Explanation: It is during the third week that the notochordal process and it's associated mesoderm induce the neural plate. The hollow notochordal process eventually becomes the solid notochord, the forerunner of the axial skeleton.

Reference: Langman’s 13th; P-43

Reference-BD Chourasia’s/7th/vol-4/p-101

[Ref. Junqueira 15th, 89]

The barriers of an oocyte are
1. First barrier is formed by cells of corona radiata
2. Second barrier is formed by zona pellucida made of
glycoproteins, ZP1, ZP2, and ZP3.
3. Third barrier is formed by vitelline membrane of oocyte itself

This ability of barrier penetration is achieved by two processes:
(a) capacitation and
(b) acrosome reaction

Prevention of polyspermy:
- Rapid depolarization of the oocyte
- Cortical reaction
- Zona reaction
- Destruction of ZP3 receptor

Mucous glands of duodenum lies in submucosa.

By the beginning of 4th month,cytotrophoblastic cells and some connective tissue cells disappear.the syncytium and endothelial wall of the blood vessels are then the only layers that separate the maternal and fetal circulation.

The structures representing all three components of embryonic disc is Tympanic membrane

Ribosome lies outside nucleus in the cytoplasm.

Unique transitional epithelium or urothelium lines much of the urinary tract, extending from the kidneys to the proximal part of the urethra, and is characterized by a superficial layer of large, dome-like cells sometimes called umbrella cells.

Reference: Langman’s 13th; P-47

(Ref: medical examination review anatomy P:41)

(Ref: medical examination review anatomy P:43)

Gap junctions (Nexus) permit the exchange between cells of molecules. Signaling molecules such as some hormones, cAMP and cGMP and ions can move through gap junctions, causing the cells in many tissues to act in a coordinated manner. Such as-the heart’s coordinated beats.

Paracortex: 
The region between the cortex and medulla, the paracor­tex or deep cortex does not have precise boundaries but can be distinguished from the outer cortex by its lack of nodules (B-lymphocytes). Paracortex mainly consists of T cells; hence, it is also called thymus-dependent cortex.

[Ref. Bailey Love's 28th]

Reference: Junqueira’s Basic Histology; 14th Edition; Page-370

Dura mater also known as pachymenix/menix fibrosa/tough mother(latin)

Merkel cell is responsible for tactile sensation

(Ref: medical examination review anatomy P:51)

Sweat glands: Stratified cuboidal
Mesothelium: Simple squamous
Fallopian tube: Ciliated columnar

Simple cuboidal epithelium is present in: 
1. Lining epithelium of thyroid follicles
2. Smaller ducts of exocrine glands
3. Covering of the ovary (germinal epithelium)
4. Choroid plexus
5. Inner surface of lens of eyeball
6. Pigmented cell layer of retina
7. Duct of Bartholin gland
8. Some part of tubules in kidney (DCT) Covering, secretion

The abdominal aorta is a continuation of the thoracic aorta beginning at the level of the T12 vertebrae. It is approximately 13cm long and ends at the level of the L4 vertebra.

[Ref. BD Chaurasia Vol.1] 

Functions of mitochondria:
1. Production of ATP by aerobic respiration
2. Mitochondrial DNA takes part in RNA & protein synthesis
3. Role in cellular catabolism by apoptosis (programmed cell death)
4. Mitochondria contains enzymes that take part in-
   a. Respiratory chain or electron transport
   b. Oxidative phosphorylation
   c. Krebs/citric acid cycle
   d. β-oxidation of fatty acid
   e. Ketogenesis

Inner mitochondrial membrane shows long infoldings called cristae (for increasing surface area).
The lipid bilayer of the inner membrane contains unusual phospholipids and is highly impermeable to ions.
Inner mitochondrial membrane is a site for oxidative phosphorylation, respiratory (electron transport) chain, and ATP synthesis.

[Ref. Junquiera 15th, 39]

Reference: Langman’s 13th; P-43

Reference: Junqueira’s Basic Histology; 14th Edition; Page-236

Aortic opening of diaphragm at the level of T12

Arachnoid and pia mater together called leptomeninges

Meckel's diverticulum is a remnant of Vitello intestinal duct

Osteocytes (Gr. osteon, bone + kytos, cell), which are found in cavities (lacunae) between bone matrix layers (lamellae), with cytoplasmic processes in small canaliculi (L. canalis, canal) that extend into the matrix

(Ref:medical examination review anatomy P:52)

Rathke's pouch and anterior pituitary develop from stomatodaeum (surface ectoderm) 

Reference: Junqueira’s Basic Histology; 14th Edition; Page-370

Base of the heart is formed by The two atria

Deep to the capsule the lens is covered on its anterior surface by a lens epithelium. The cells of the epithelium are cuboidal. However, towards the periphery of the lens the cells become progressively longer. Ultimately, they are converted into long fibres that form the substance of the lens.

Reference-BD Chourasia’s/7th/vol-4/p-173

Functions of SER:
1. Synthesis of lipid: SER is the main site for synthesis of lipid
2. Carbohydrate metabolism
3. Synthesis of phospholipids
4. Detoxification of potentially harmful exogenous molecules such as alcohol & barbiturates in liver
5. Synthesis of steroid hormones
6. Synthesis & storage of cholesterol
7. Participate in contraction process in muscle cells (sarcoplasmic reticulum)

Functions of RER:
1. Protein synthesis: Site for translation (mRNA -> protein)
· Membrane associated proteins
· Proteins of membranous organelles
. Proteins to be secreted by exocytosis
2. Initial glycosylation of glycoprotein
3. Post-translational modification of protein
4. Assembly of multichain proteins
5. Checkpoint: RER destroys defective proteins

Vestibulocochlear nerve is originated from PM junction.

The inferior vena cava passes through the diaphragm at the vena caval foramen. This aperture is located in the central tendon at the level of T8.

The processes of astrocytes are united to those of other astrocytes through gap junctions. Astrocytes communicate with one another through calcium channels. Such communication plays a role in regulation of synaptic activity and in the metabolisms of neurotransmitters and neuromodulators.