Railway Science (Biology-Reproduction in Animals) (Part-II)

The crossing between two different species of the same genus (produce a new variety called hybrid) is known as interspecific crossbreeding. Animals involved with their hybrid name : Female donkey and a male horse - Hinny, Donkey and Zebra - Zebroid, Horse and Zebra - Zorse, Female tiger and a male lion - Liger, A cross of an American bison and a domestic cow - Beefalo, A cross between the Asian leopard cat and the domestic cat - Bengal Cat.

Fraternal twins (dizygotic twins) - Result from the fertilization of two separate eggs with two different sperm during the same pregnancy. It may not have the same sex or appearance.They share half their genomes, just like any other siblings.
Identical twins (Monozygotic twins) - The fertilization of a single egg by a single sperm, with the fertilized egg then splitting into two. Zygotic stage - Represents the first stage in the development of a genetically unique organism.

Gene Annotation - It involves taking genomic data - DNA or RNA sequences and mapping the correct genes to the correct locations. Gene expression : The process by which the information encoded in a gene is turned into a function.
DNA Sequence Assembly : It is a process that involves aligning and merging fragments of a DNA sequence to reconstruct the original structure of the DNA. Proteomics : The study of the interactions, function, composition, and structures of proteins and their cellular activities.

A test-tube baby is a baby who is conceived by In vitro Fertilization (IVF) technique. In this fertilization is done outside the uterus in a glass vessel by combining a female egg with a Male sperm. Once the egg is fertilized it is implanted into a woman’s uterus with the help of a catheter. Louise Joy Brown was the world's first test-tube baby.

Ovarian follicles : A spherical cellular aggregation present in the ovaries. Graafian follicle : A follicle that ruptures and releases its ovum when stimulated. It is present inside an ovary and is a minute cyst within which an egg develops. Generally, women are born with many undeveloped follicles, each containing an immature ovum.

A eukaryotic cell formed by a fertilisation event between a female gamete (egg or ovum) and a male gamete (sperm). Gamete - It is used to describe the reproductive cells of animals or plants.
Blastula - It is a hollow spherical layer of cells (blastoderm) produced during the development of an embryo, surrounding a fluid-filled cavity (blastocoel). Gastrulation - It is the process during embryonic development that changes the embryo from a blastula with a single layer of cells to a gastrula containing multiple layers of cells.

Chromosomes are thread-like structures located inside the nucleus of animal and plant cells. Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA).
Some animal and plant chromosomes - Humans (46), Pea (14), Kangaroo (16), Carrot (18), Rice (24), Earthworm (36), Cat (38), Dolphin (44), Mango (40), Onion (16), Tomato (12), Lion (38).

Uterus (Womb): It is a female reproductive organ found in humans which is responsible for developing and sustaining the fetus. Cervix is the lower end of the uterus. During pregnancy, it remains closed to support and protect the developing fetus until labor, when it dilates for childbirth.
Vagina - A muscular canal connecting the uterus to the outside. It allows sperm entry for fertilization and serves as the birth canal during childbirth.

Placenta is an organ that develops in the uterus during pregnancy. This structure provides oxygen and nutrients to a growing baby.
It also removes waste products from the baby's blood. The placenta attaches to the wall of the uterus, and the baby's umbilical cord arises from it.
Embryo - the early stage of development of a multicellular organism, following fertilization and preceding full gestation.

The male germ cells are spermatogenic cells, present in the epithelial layer of the seminiferous tubules. The testes are located in the scrotum. The sperms formed are delivered through the vas deferens which unites with a tube coming from the urinary bladder.
Prostate glands and the seminal vesicles add their secretions so that the sperms are now in a fluid which makes their transport easier and this fluid also provides nutrition.