Write a note on: (i) Lactation in humans (ii) Gemmule (iii) Cockroah ovaries
Answers
heyyyy mate.....
LACTATION IN HUMANS ----
The process of milk production. Human milk is secreted by the mammary glands, which are located within the fatty tissue of the breast. The hormone oxytocin is produced in response to the birth of a new baby, and it both stimulates uterine contractions and begins the lactation process. For the first few hours of nursing, a special fluid called colostrum is delivered; colostrum is especially high in nutrients, fats, and antibodies, to protect the newborn from infection. Thereafter, the amount of milk produced is controlled primarily by the hormone prolactin, which is produced in response to the length of time the infant nurses at the breast.
GEMMULE ----
An asexually produced mass of cells, which are capable of developing into a new organism or into an adult freshwater sponge is termed as a Gemmule. They are small bud like cells, which are formed by sponges to withstand unfavorable environmental conditions. A freshwater sponge reproduces both by sexually and asexually.
Asexual reproduction is mainly carried out by budding and also by gemmulation. The internal buds, which are formed by the freshwater sponges are called as gemmules. These gemmules are tough and coated with a dormant cluster of embryonic cells. Freshwater sponges are multicellular, marine living species of a Kingdom Phylum – Porifera. The species of this kingdom includes sponges, Ficulina ficus, sea sponges and much more. All the species related to the same kingdom and carry same characteristic features.
COCKROACH OVARIES ---
There are two large, light yellow- coloured ovaries lying laterally in the segment 4th, 5th, 6th, embedded in the fat body. Each ovary is formed of a group of eight ovarian tubules or ovarioles containing a chain of developing ova. An ovariole is made up of an epithelial layer resting on a basement membrane and enclosed externally in a connective tissue coat.
However, an ovariole from in front to backwards consists of the following zones:
(i) Suspensory filament, it is thin, thread-like continuation of the connective tissue layer and provides attachment of the ovariole to the dorsal body wall and, thus, it serves to suspend the ovariole in the haemocoel.
(ii) Zone of germarium, it follows the terminal filamentous zone and consists of germ cells or oogonia and mature into oocytes and pushed downwards.
(iii) Vitellarium, this zone receives the oocytes from the zone of germarium one by one and constitutes the largest part of the ovariole, the oocytes become enclosed in a follicle of epithelium and increase progressively in size towards the posterior end which gives it beaded appearance.
(iv) Egg chamber, the vitellarium opens posteriorly into a small, thick, oval egg chamber which contains a single large mature ovum at a time.
(v) Stalk or pedicel, the egg chamber continues posteriorly into thin-walled, hollow stalk which opens into the lateral oviduct.
hope it helps.....
plzzz mark as brainliest......