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CONCEPTUS AND FOETAL DEVELOPMENT

Conceptus and fetal development in mammals

By ghulam mohyuddin wani and gazanfer wani

Cleavage in Mammals

      Four maternal effect genes (MEG) namely

(i)           Zygote arrest I (ZARI)

(ii)       Maternal Antigen That Embryo Requires (MATER)

(iii)   Growth Differentiation Factors 9 (GDF 9)

(iv)    Bone Morphogenetic Protein 15 (BMP 15)

The above named factors were determined in ovine oocyte, and invitro produced bovine pre-implantation embryos. The existence of ZARI and MATER were in abundance in ovine immature oocytes than in cleaved zygotes, morulae or higher developed forms.With maturation and maternal-embryonic transition the transcription of the above four genes did not resume. Even activation of the genome did not help to restore their transcription. Does it mean these MEG determine easily or initiation of cleavage is postulated  by Daniele Babere, Babere, D et al 2008 in  Reproduction Fertility and Development .20 (8): 908-915

              Expression pattern of zygote arrest I (ZARI), maternal antigen that embryo requires (MATER), growth differentiation factor 9 (GDF 9) and bone morphogenetic pattern 15 (BMP 15) genes in ovine oocytes and in-vitro-produced pre-implantation embryos. Bebbere, D, Bogliolo, L, Arile, F, Fois, S, Leoni, G-G, Naitana, S and Ledda, S 2008.

          The arrangement and formation of placenta, umbilical cord in ovines as an example of mammalian placental differentiation can be viewed from our results (Wani et al. 2006, Khatun 2007). Conceptus or foetus takes its oxygen from mothers blood, via umbilicus, this necessiciates a special mechanism of interwoven capillary network over the foetal amnion. This consulted junction of capillary network gives an impression of a large telephone exchange interwoven into junction, sub junction, joints and networking. The separation of actual foetus by amniotic covers and arrangement of cotyledon formation and unions with maternal epithelium can be seen in figs 25-30. a series of foetal development age wise can be seen in the figures cited. A new method of foetal age determination has been evolved and is known as Wani-Khatun foetal age determination Charh (Table 2). The crown-rump length has been replaced with whole foetal length formula. This estimation graph shall help human and animal gynecologists to determine foetal age at ultrasonography.

       The development of organs in the foetus starts around day 25. some of the foetal parts can be seen even earlier in the figures shown and quoted in preceding page. The organ development in human is as

Day 25                :     Head and trunk seen tiny arms buds leg bud in formation

Early Embryo            :      Has a tail, which seems to be a protective covering

       For the spinal cord. This tail like spinal cord protection can also be seen in ovine developing foetus. This protection ensures safety of brain, spine and spinal cord.

       The human fetal heart starts beating around 21-25 days. ovine heart beats were recorded using ultrasonogrphic equipments as easily as 25 day (Wani & Sahni, 1981, Wani, 1981, 181, 1984). The crown-vump length of 29 day foetus / conceptus is 5.0mm. this one month old fetus has;

Diameter ¼ of an inch has a brain, Eye, Mouth, Kidneys, Liver, Heart, Umbilical Cord

2nd month foetus

size 44 mm (maximum at 42 days foetus measured 23 mm. fingers are identified eyes and ears, lends and retina appear to develop first eyelids inner ear and outer ear. Hearing and balancing mechanism. The sense of hearing is established. Skeletons cartilaginous but full formed. The skeletal cartilaginous framework of the baby (exactly as described in Surrah Momineen of Quaran 1430 years ahead. This is by for the first written reference of foetal development around12 weeks, the foetal movements are possible. However strong movements of bony Skelton holding foetus, which can be registered by mother are realized by about 6 months of pregnancy.

       Now-a-days electro-encephalograph (EEG) of foetus is possible which has shown that brain waves in early embryo can be dete4cted around 40 days after fertilization .

       By 35 days CRL is 12-14 mm CRL (Crown Rump Length).

       Sense of touch has been reported from mouth area around 6-7 weeks after fertilization and soles of feel can be felt on pinch around 8-9 weeks . Sensory nerve development during 2nd month is thought to be the reason for this movement stimulus. Nerve fibers at this age respond tot stimuli of touch and induce movements of the foetus. Sensory nerve of developing foetus is more sensitive than adult or newborn baby. Does it mean that those amphibian whose nerves can regenerate and give rise to new limbs once one of their limb is cut or broken, have more sensitive nerve tissues. Can be thick of studying these nerve promoters and make use of then inhuman paralytic or neuron-recovery therapeutics can this be our new option for “Neurosurgery”.

Foetus

       Around 8weeks, the cartilaginous skeleton of the embryo is being replace by bone. The body is complete and embryo can be safely denoted as “Foetus”.

       In ruminants a set definition of embryos, foetus, has been made and shall be discussed under comparative narration of this chapter.

       Foetus is a Latin word, meaning young offspring. Here let us make it clear that the  names of developing conceptus at differential growth stages and development process has been described as;

a)              Oocyte: Primary oocyte within follicles

b)             Ovum /Egg: The matured secondary oocyte released at ovulation

c)              Zygote / Morulae: A fertilized oocyte with cleavage and many cells appear as a berry-Morulae

d)             Embryo: A developing morulae, early late morulae.

e)              Blastocyst: One a cavity Blastocoeal develops

f)               Conceptus Formation of placent, cotyledons, carunds, placentom

g)             Foetus : Fully formed bony structured embryo or conceptus

 

Third Month Development

Diameter 90 mm, Weight 45 gms , Broad face

Closed eyes. Boy or girl can be differentiated. Foetal fingers can move and bend around an object. Curling of toes to touch  close to open palm and moth (8). Nerve fibers developed to register pain first trimester baby is more responsive than older, thus registering more pain. Thus pain registering mechanism is developed earlier than pain recording or feeling mechanism. It mean pain sensing and its objective registering is different. In it’s the case in consciousness loss patients. Can be bring back sensation through in-corporation of these nerve cells or can be help cure of paralysis by inducing this type of premature cell materials, in other worlds, reception, transmission and perception or primitive pain sensation occurs during this period.

       Swallowing amniotic fluid starts around 11 weeks after conception. Facial expression like smile or anger has been seen during this period. Swallowing and thumb sucking has been recorded by (13), Breathing (14), movements can be felt, but actual breathing is a postnatal function  and not a neonatal activity.

Four-Five Month

       CRL- 140 mm diameter this approximately 33 % of the newborn baby size. It weights 200 grams and the foetal heart has a capacity of pumping 30 liters of blood in a day. Uterus grows and womb appears to show itself as a “Bulge” the fundus i.e. top of uterus between fallopian tubes can be felt as it stretches towards chest. From four months onwards foetus responds to sounds. Deafness can be detected at this stage too eye movement and blink – startle starts around d16-35 weeks (15).

       Foetus hears inside womb within amniotic fluid, but an adult swimmer does not hear while in water. The reason the air around ear canal of the adult is missing in the foetus. So if one wishes to hear within water, (air0 in canal of ear has to be replaced with tight acostic materials. Does finds provide such a system to whales or other mammalians living in the water. Thus the silent world of fantasy within womb has many more exciting inventions for the world. The foeuts is subjected to sounds of uterine entry blood gush, heart and respiratory sounds too. Music preference, babies learn to recognize their mothers voice while in womb. In this the “mother instinct” so common in animals.

       Response to light is first seen around 16th week. Light on mothers abdomen increases foetal heart beats.

 

20 weeks CRL 190mm, Weight 460 gms, Head, Hair, Eye Brows, Eyelashes and nails are growing. Developing fetal baby has a greasy substance called vernx over its body. It is a shining, glistering coat seen in ovine around d3-4 months of gestation (Fig. 30-35) (Mufti et al. 1995, 2000,  Khatoon, 2007,  Wani et al 2006, 2007, 2008, 2009)

       immune systems also start developing during this period. Foetus active when mother sleeps, or rests baby kicks are common during night wakening, sleeping and rapid movements are shown by foetus in this stage too. Comfort positioning vis-in-vis babies of 22-27 weeks age cn be reared outside womb with 72% success.

       The formation of a human being is destined (Al. Quran) it is proved by recent investigation of Embryology as every one-cell zygote behaves individually and is an individual identity as is a fully formed man. The behaviors and manners of sleep, movements, reaction as in womb are almost same at birth. This directed differentiation procedures have cure for such dieses as Biabets, Parakinsons diease, spinal cord injury, pinkinje cell differentiation, Duchenne’s muscular dystrophy, heart diseases, vision and hearing losses.

       Any undifferentiated cell within a tissue whose cell have differentiated to give it that peculiar tissue shape can be called as an adult stem cell. This undifferentiated stem cell has the capacity to give rise to any cell type. They can be called repairs cell within that tissue, they are usually called somatic cells. They differ with embryonic stem cells. Embryonic stem cells are recovered from blastocyst inner cell mass and are totipotent. They can give rise to any cell type. Somatic cells have been found in mammary glands, bone marrows. As long as the embryonic stem cells in culture are grown under certain conditions, they can remain undifferentiated (unspecialized). But if cells are allowed to clump together to form embryoid bodies, they being to differentiated spontaneously can form muscle cells, nerve cell sand many other cell types. Although spontaneous differentiation is a good. If scientists can reliably direct the differentiation of embryonic stem cells into specific cell types, they may be able to use the resulting, differentiated cells to treat certain disease at some point in the future. Diseases that might be treated by translating cells generated from human embryonic stem cell include Parkinson’s disease, diabetes, traumatic spinal cord injury, purkinje cell degeneration, Duchenne’s muscular dystrophy, heart disease, and vision and hearing loss.

ADULT STEM CELL/somatic cell

An undifferentiated cell within differentiate cell of a tissue can be called as an adult stem cell. This cell has the capacity to give rise to any type of cells and can be utilized as repair cells. These cells are also called somatic cells.    They  are different then the embryonic stem cell which are recovered from the blastocyst inner cell mass and are totipotent and can give rise to any cell types.

Somatic cell have been found in many tissues like the mammary gland somatic cell origin of dolly the sheep. Bone marrow cells  have been used in the past and many other cell types are now used. The foetal cell are known to be inert cell, can they be used for recovery of stem cell has been prophesed (Wani, 2009) .

If these cell can differentiate in situ ,we may find cure to many diseases. God has provided his greatness in the milk of kangaroo, as a antibiotic rich source which can kill germs a thousand times quicker and efficiently than any known antibiotic.

 Many such facts are hidden in the foetomaternal placentala which may reduce the cost of stem cells to affordable levels as antibiotics. The knowledge of haemopiotic stem cells from mammary gland and other tissues may revolutionize their use in future. The old myth of nerve cells being having no ability to divide but grow only kept doctors wondering for years This made a negative impact to cure nerve damages  difficult.Today we know they multiply too,who knows in the future we have the mechanism of rebuilding nerves and amputated limbs like amphibian  animals inhibiting . The brain division and possibility of nerve growth and regeneration of past discoveries was shyed out and led to a dark phase of ignorance being regard as a scientific truth. Thus science has to believe as was in past that what we know today may lead to many more inventions in the future. Now we know that the adult brain is able to generate astrocysts, oligodenrocytes and neurons or nerve cell too. Adult stem cells are now found in brain, blood cells, blood vessels, liver, skin and skeletal muscles thus giving much hope to contain diseases in future. These cells when grown in culture can help to cure disease of the ailing tissue and organs.

        Hematopoietic stem cells give rise to all the types of blood cells, red blood cells, Blymphocytes, T lynmphocytes, natural killer cells, neutrophils, basophils, eosinophils, monocytes, macrophages and platelets

        Bone marrow stomal cells (mensenchymal stem cell) give rise to a variety of cell types, bone cells (osteocytees), cartilage cell (chondrocytes), fat cell (adipocyte), and other kinds of connective tissues cell such as those intendons. Neural stem cell in the brain give rise to its three major cell types, nerve cells (neurons) and two categories of non-neuronal cell-astrocytes and oligodendrocytes. Epithelial stem cells in the lining of the digestive tract occur in deep crypts and give rise to several cell types, absorptive cells, goblet cells, paneth cells, and enteroendocirn cells.

        Skin stem cells occur in the basal layer of the epidermis and at the base of hair follicles. The epidermal stem cells give rise to keratinocyts, which migrate to the surface of the skin and form a protective layer. The follicular stem cells can give rise to both the hair follicle and to the epidermis

TRANSDIFFERNTIATION 

It was the belief that only erly embryonic cells are plueripoten and not the somatic or any other cells,STEM CELL RESEARCH has show that a  number of  adult stem cell type are pluripotent too. Their  ability to differentiate into multiple cell types is called plasticity or transdifferentiation in comparison to embryonic stem cells where it was named as pluripoten and differentiation. The following  adult stem cell plasticity that have been reported during the past few years.

         Hematopoietic stem cells

   Three major types of brain cell (neurons,       oligodendrocytes and astrocytes);

 skeletal muscle cells;

cardiac muscle cells, and

 liver cells

Bone marrow stromal cells may differentiate into:

 cardiac muscle cells and

skeletal muscle cells

Brian stem cells may diferrentitae into

Blood cells and

skeletal muscle cells

TISSUE REPAIR

 The  mechanism of   adult stem cell plasticity if identified and controlled ,existing stem cell  from a healthy tissue might be induced to repopulate and repair a diseased tissue.

        Many important question about adult stem cells remain to be answered. They include:

How many kinds of adult stem cells exist, and in which tissues to they exist?

        What are the sources of adult stem cells in the body? Are they “Leftover”  embryonic stem cells, or do they arise in some other way? Why do they remain in an undifferentiated state when al the cell around them have differentiated?  Do adult stem cells normally exhibit plasticity, or do they only transdifferentiate when scientist manipulate them experimentally? What are the signals that regulate the proliferation and differentiation of stem cells that demonstrate plasticity? Aschematic diagram obtained from the website is reproduced here to understand the phenomenon of stem cell production. Many question at the moment remain unanswered .could be possibly explained in future.

 

 

           

 

 

 

 

 

 

 

 

 

 

 

 

           

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