Embryonic Development

Maternal nutrition plays a vital role in the growth and development of the fetus. During prenatal development, the fetal circulatory system is integrated with the placenta via the umbilical cord so that the fetus receives both oxygen and nutrients from the placenta. The placenta is an organ that develops in your uterus during pregnancy. This structure provides oxygen and nutrients to your growing baby and removes waste products from your baby's blood. The placenta attaches to the wall of your uterus, and your baby's umbilical cord arises from it.

Neuroectoderm gives rise to the following compartments of the eye: retina, epithelial lining of ciliary body and iris, optic nerves. Surface ectoderm produces the following parts: lens, corneal epithelium, skin of eyelid.

In biological development, the zygote undergoes cleavage to become a blastocyst and then develops into an embryo.

The life cycle begins with fertilization, resulting in a single-celled zygote (the egg).

When the tunica is multilayered, the condition is called multistratose tunica. The layers of tunica can be designated as L1, L2, L3 and so forth. The L1 or the outermost layer of the tunica would give rise to the epidermis and the rest of the layers would form the cortex and the vascular tissues, as seen in Datura.

'Gastrulation' word is derived from Greek word 'gaster' meaning stomach and according to McEwen (1923), gastrulation refers to the formation of the primordial gastric gut or cavity called the archenteron.

In organogenesis, cells of the three germ layers lead to the formation of specific structures. The ectoderm eventually forms the outer layer of the skin and gives rise to the nervous system and sense organs. Tissues that eventually line the digestive tract and organs like liver, pancreas and lungs are all of endodermal origin. Skeletal tissue, muscle, and the circulatory, excretory, and reproductive systems are derived from mesoderm.

The cotyledons are attached to the curved embryonal axis (Tigellum) at the cotyledonary node. The ,micropylar end of embryonal axis is rod- shaped and slightly bulged. It is called radicle (or embryonic root). The other side of embryonal axis lies in between the two cotyledons. It is called plumule( or the shoot tip).

In human prenatal development, the organism is called an embryo from implantation until the end of the eighth week. From the ninth week (the start of the third month) until birth, it is referred to as a foetus.

In human prenatal development, the offspring is called an embryo from conception until the end of the eighth week. From the ninth week (start of the third month) until birth, it is referred to as a fetus (or foetus).

Mesoderm is the middle embryonic germ layer that gives rise to connective tissues, bones, muscles, and the circulatory system. Ectoderm primarily forms the nervous system and skin epidermis, while endoderm forms the epithelial linings of the digestive and respiratory tracts.

Pluripotent cells can differentiate into nearly all cell types of the body, but they cannot form the extraembryonic tissues that surround and support the embryo. Totipotent cells, on the other hand, have the ability to form both the embryo and these extraembryonic tissues.

Embryonic stem cells derived from the inner cell mass of a blastocyst are pluripotent, not multipotent. Pluripotent cells can give rise to almost any cell type in the body, whereas multipotent stem cells are more restricted and can only develop into a limited range of cell types.

From a biological standpoint, the germ (or germinal disc) is the most important part of the egg because it contains the genetic material and is where embryonic development begins if the egg is fertilized. However, the phrasing 'most important part' is somewhat subjective.