Quick Answer: What Is Theca?

What is the theca Folliculi?

Definition of Theca cell The theca folliculi comprise a layer of the ovarian follicles.

They appear as the follicles become secondary follicles.

The theca are divided into two layers, the theca interna and the theca externa..

Why anther is called Dithecous?

A typical angiosperm is bilobed with each lobe having two theca. Hence angiosperm anther are called dithecous. … When the anther is young, a group of compactly arranged homogenous cells called sporogenous tissues occupies the centre of each microsporangium which produce micro spores or pollen grains.

What is the structure of anther?

The fertile portion of stamens is called anther. Each anther is usually made up of two lobes connected by a connective. In turn each anther lobe contains two pollen chambers placed longitudinally. All pollen grains of an anther lobe remain united in a sac called pollinia.

What is theca in biology?

The theca of an angiosperm consists of a pair of microsporangia that are adjacent to each other and share a common area of dehiscence called the stomium. Any part of a microsporophyll that bears microsporangia is called an anther. … Each theca contains two microsporangia, also known as pollen sacs.

What do theca cells do?

Theca cells are the endocrine cells associated with ovarian follicles that play an essential role in fertility by producing the androgen substrate required for ovarian estrogen biosynthesis. Theca cells differentiate from the interfollicular stroma in response to proteins secreted from growing follicles.

Where do theca cells come from?

Theca cells originate from progenitor cells within the ovary and an adjacent fetal structure, the mesonephros. The ovary consists of a variety of cell types, each with distinct cellular origins. Granulosa cells, which surround the growing oocyte, originate with the epithelium that encases the ovary.

How many theca are there in anther?

two thecaA typical angiosperm anther is bilobed with each lobe having two theca, i.e., they are dithecous (Figure 2).

What stimulates theca?

luteinizing hormoneTheca cells are stimulated by luteinizing hormone (LH), with signaling originating in the hypothalamus of the brain. Gonadotropin releasing hormone (GnRH) is released by projections of the hypothalamus into the anterior pituitary gland.

What does thecal sac mean?

Thecal sac is the outer covering of the spinal cord. This means there are bone spurs on the back of the spinal bones, putting pressure on or affecting the front part of the outer layer of the (neck) cervical spinal cord.

What is the pollen sac?

: one of the pouches of a seed plant anther in which pollen is formed.

Where are theca cells located?

ovaryIntroduction. Theca cells are endocrine cells located exclusively in the ovary (Erickson, Magoffin, Dyer, & Hofeditz, 1985). The follicle is the basic functional unit of the ovary, containing a single oocyte and granulosa cells enclosed by a basal lamina.

What does theca externa secretes?

The theca externa is a connective tissue layer derived from fibroblast-like cells that produce extracellular matrix factors, such as collagen. … Specifically, GDF9 secreted from the oocyte induces the expression of IHH and DHH in granulosa cells.

What is Micro Sporogenesis?

[ mī′krə-spôr′ə-jĕn′ĭ-sĭs ] The formation of microspores inside the microsporangia (or pollen sacs) of seed plants. A diploid cell in the microsporangium, called a microsporocyte or a pollen mother cell, undergoes meiosis and gives rise to four haploid microspores.

What is lobes in anther?

Most commonly anthers are two-lobed and are attached to the filament either at the base or in the middle area of the anther. The sterile tissue between the lobes is called the connective, an extension of the filament containing conducting strands. It can be seen as an extension on the dorsal side of the anther.

How many Microsporangia are present in each flower of Solanaceae?

Answer: Each microspore mother cell gives rise to a pollen tetrad. Thus, 10 flowers (with 10 stamens in each) having 30 microsporangia in each microsporangium will form 48,000 pollen grains.

What does mean theca?

: an enveloping sheath or case of an animal or animal part.

How many theca are in the anther?

two thecaA typical angiosperm anther has two parts, an anther and a slender, thread like filament. Each anther is a bilobed structure, i.e., it has two lobes, and each lobe is dithecous i.e., has two theca. Each theca has a mass of sporogenous tissue which develops into microsporangium or pollen sac.

What does theca produce?

Theca cells: LH, progesterone, and androgens Theca cells (Fig. 4.9) produce pregnenolone from cholesterol. Pregnenolone can be converted to progesterone. In the ovaries, once converted, progesterone cannot be converted to androgens or estrogens.

Do granulosa cells produce estrogen?

Estradiol production Granulosa cells of the ovulatory follicle are the major and virtually only source of estradiol in the follicular phase of the ovarian cycle and secrete estrogens in response to FSH.

Is anther Dithecous or Tetrathecous?

1. A typical young anther is bilobed, tetrathecous and tetrasporangiate. 2. A typical mature anther is bilobed, dithecous and tetrasporangiate.

Is anther Dithecous?

A stamen or male reproductive organ of a flower is made up of two parts- a stalk-like filament and a knob like terminal anther. Each anther has two lobes which are attached at the back by a sterile band called connective. When both the anther lobes are present, the stamen is called bithecous(or dithecous).