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Compiled by I. Abdullah.

This post is “work in progress”. Last updated on the 28th April 2013, 21:00  Any comments are most welcome.

Figure 1: 50 Day Human Embryo (Stage 20) and a photo-micrograph and magnetic resonance image (MRI) of the same embryo. (1)

The Qur’an mentions that human development passes through a number of distinct stages (Qur’an 39:6 and 71:14). These stages are descriptive of the embryo’s external appearance and have been assigned the following names as we read in Surah Al-Mu’minoon (The Believers) 23: 12-14:

And We (God) created man from a quintessence (gentle extraction) of clay. We then placed him as a nutfah (drop) in a place of settlement, firmly fixed (i.e. the womb). Then We made the drop into an ‘alaqah (clinging form), and then We changed the clinging form into a mudghah (chewed-like form), then We made out of that chewed-like form, izam (skeleton, bones), then We clothed the bones with lahm (muscles, flesh), then We (ansha’ nahu), caused him to grow and come into being and attain the definitive (human) form. Blessed be God, the Perfect creator.

This article briefly describes the Izam (skeleton, bones) and Lahm (muscles, flesh) stages of development.

The Izam stage

Figure 2: Human embryo at Stage 20 showing the cartilage skeleton. About days 50-51 days (Ulrich Drews, Color Atlas of Embryology, 1995). (2)

then We made out of that chewed-like form, izam (skeleton, bones)

The stage of development after the chewed-like form (mudghah) is referred to as izam which means “bones” (3) and the fetus does indeed acquire a cartilaginous skeleton of bones. In the 6th week the cartilaginous skeleton begins to form and the embryo acquires a soft skeleton as we see in Figure 2.

“Formation of bone does not begin uniformly throughout the body. Rather, there is a sequential appearance of bony tissue. However, in the 7th week the spreading development of the skeleton occurs. Bone development in the limbs commences in the limb buds from mesochymal cells. Primary ossification centers appear in the femur during week 7 and in the sternum (breast bone) and the maxilla (upper jaw) in weeks 8-9.” (4)

Mesenchymal bones are made out of connective tissue which become cartilaginous, and then they become ossified and become (solid) bones. Mesenchymal bones form during the fifth week as condensations of mesenchyme appear in the limb buds (Figure 3 A to C). During the sixth week, the mesenchymal bone models in the limbs undergo chondrification to form hyaline cartilage bone models as wee see in Figure 3 D and E.

A, Photograph of an embryo at approximately 28 days showing the early appearance of the limb buds. B, Longitudinal section through an upper limb bud showing the apical ectodermal ridge, which has an inductive influence on the mesenchyme in the limb bud. This ridge promotes growth of the mesenchyme and appears to give it the ability to form specific cartilaginous elements. C, Similar sketch of an upper limb bud at approximately 33 days showing the mesenchymal primordia of the forearm bones. The digital rays are mesenchymal condensations that undergo chondrification and ossification to form the bones of the hand. D, Upper limb at 6 weeks showing the cartilage models of the bones. E, Later in the sixth week showing the completed cartilaginous models of the bones of the upper limb.

Figure 3 A, Photograph of an embryo at approximately 28 days showing the early appearance of the limb buds. B, Longitudinal section through an upper limb bud showing the apical ectodermal ridge, which has an inductive influence on the mesenchyme in the limb bud. This ridge promotes growth of the mesenchyme and appears to give it the ability to form specific cartilaginous elements. C, Similar sketch of an upper limb bud at approximately 33 days showing the mesenchymal primordia of the forearm bones. The digital rays are mesenchymal condensations that undergo chondrification and ossification to form the bones of the hand. D, Upper limb at 6 weeks showing the cartilage models of the bones. E, Later in the sixth week showing the completed cartilaginous models of the bones of the upper limb. (The Developing Human Clinically Oriented Embryology 9th edition, by Moore et al).

The timing of the izam phase has been mentioned in the following Hadith (Sahih Muslim, Kitab Al-Qadar):

When 42 nights have passed from the time of the nutfah (time of conception), God sends an angel to it, who shapes it and makes its ears, eyes, skin, muscles and bones…

“In the early part of this (izam) phase, the embryo takes on a human appearance (tasweer adami), and the hadith describes this with the word “shapes”. Before the 42nd day, it is difficult to distinguish the human embryo from the embryos of many animals, but at this time it becomes clearly distinguishable in its appearance.” (4)

The formation of the skeleton gives the embryo its human shape.

The Lahm stage

Figure 4: Diagram showing Early Forelimb Skeleton in the sixth week. (Wendell Smith, C. P., Peter L. Williams, and Sylvia Treadgold. Basic Human Embryology. 3rd ed. London: Pitman, 1984) (6)

then We clothed the bones with lahm (muscles, flesh)…

The next stage is the lahm stage (muscles, flesh) stage. The lahm stage is characterized by clothing the bones with muscles (al-kisa’ billahmn). During the lahm stage, the embryo develops human features, and the various organs assume their proper positions and are better proportioned. Thus during this stage the effect on the embryo of muscles clothing the bones is manifest in its external appearance.

“Soon after the cartilaginous models of the bones have been established, the myogenic cells, which have now become myoblasts, aggregate to form muscle masses on the ventral [front] and dorsal [back or posterior] aspects of the limbs.” (5)

Profs. Smith and Williams state that:

Muscles are first indicated as premuscle masses of condensed mesenchyme in the base of the limb bud [Figure 4]. Myoblasts become spindle-shaped and arrange in parallel bundles in which they fuse end to end, forming long multinucleate myotubes. Myofibrils appear within the myotubes and, increasing in number and size, develop cross-straitions.The final number of fibres in a muscle is reached sometime before birth. Muscles then grow by the increase in length and thickness of individual fibres and by the addition of myoblasts at their ends. As differentiation proceeds proximodistally [from the shoulder to the tips of the digits] within the limb bud premuscle masses are formed dorsal and ventral to the developing bone. Flextor and adductor muscles develop in the ventral mass and extensor and abductor muscles in the dorsal mass.” (6)

The primordia from which the bones and muscles develop are formed before the 7th week, differentiation of the skeleton occurs in the 7th week and differentiation of the muscles occurs next in the 8th week:

Although precursor cells (myoblasts, or primitive muscle cells) are present adjacent to developing bone, differentiation into skeletal muscle attachments occur after the ossification process in the shaft and ends of the bones has begun.

A major developmental landmark during the eighth week is the lahm stage, which describes the myogenesis (muscle formation) period, and which marks the development of definitive muscles in the trunk and limbs and the beginning of movement. The muscles take their position around the bones (“clothing the bones”) and continue the process of straightening and smoothing (taswiyah) which began in the izam stage.” (4)

[The] muscles and tendons become attached to the bony structures so that they can produce their actions across the joints.” (5)

Figure 5: Human embryo at Stage 20 showing the skeletal musculature. About days 50-51 days (Ulrich Drews, Color Atlas of Embryology). (2) The lahm stage is characterized by “clothing the bones with muscles” (al-kisa’ billahmn).

The Lahm stage begins from the about the end of the 7th week to the end of the 8th week and comes immediately after the izam stage.

Figure 2 and Figure 5 show a human embryo at Stage 20 (about days 50 – 51 days) showing the cartilage skeleton and skeletal musculature.(2) For further information on bone and muscle development see Embryology in the Qur’an: Bone and Muscle Development (4).

Note From a Reader: The development of the Meckel’s cartilage

The abstract of a paper published in Anatomical Science International on development of the Meckel’s cartilage may be of interest to your readers.  The Meckel’s cartilage is a cartilaginous bar in the fetus around which the mandible (jaw bone) develops. Part of Meckel’s cartilage develops into the malleus (an ear ossicle) in the adult. Note the sequence of the development of the Meckel’s cartilage:

“The Meckel’s cartilage itself and the mandible are derived from the first branchial arch, and their development depends upon the contribution of the cranial neural crest cells. The prenatal development of the Meckel’s cartilage, along with its relationship to the developing mandible and the related structures, were studied histologically in human embryos and fetuses. The material was obtained from a collection of the Department of Anatomy, and laboratory procedures were used to prepare sections, which were stained according to standard light-microscopy methods. The formation of the Meckel’s cartilage and its related structures was observed and documented. Some critical moments in the development of the Meckel’s cartilage are suggested. The sequential development of the Meckel’s cartilage started as early as stage 13 (32 days) with the appearance of condensation of mesenchymal cells within the mandibular prominence. During stage 17 (41 days), the primary ossification center of the mandible appeared on the inferior margin of the Meckel’s cartilage. The muscular attachments to the Meckel’s cartilage in embryos were observed at stage 18 (44 days).

Wyganowska-Świątkowska M, Przystańska A. The Meckel’s cartilage in human embryonic and early fetal periods. Anat Sci Int. 2011 Jun;86(2):98-107. doi:10.1007/s12565-010-0093-3. Epub 2010 Aug 27. PubMed PMID: 20799009.

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Footnotes

(1) The Multi-Dimensional Human Embryo, Stage 20, Day 50.

(2) Ulrich Drews, Color Atlas of Embryology, Thieme Medical Publishers, 1995. Page 98-99. Showing the cartilaginous skeleton of an embryo at stage 20 (about day 50 – 51, 18 – 22 mm).

(3) Izam meaning “skeleton, bones”. The term encompasses both cartilage and ossified (hard) bone. This post refers to the development of the appendicular skeleton which consists of the pectoral and pelvic girdles and the limb bones.

(4) G. C. Goeringer, A. A. Zindani, M. A. Ahmed, Embryology in the Qur’an: Bone and Muscle Development. http://islampapers.com/2012/03/06/bone-and-muscle/

(5) John Allan and Beverley Kramer, The Fundamentals of Human Embryology. 2nd Edition. Wits University Press. 2010, page 148.

(6) C.P. Wendell Smith and P.L. Williams, Basic Human Embryology, 3rd Edition, London, Pitman Publishing Ltd., 1984, p. 114.

(7) Video: Embryology in the Qur’an by Dr. Keith Moore (1990). University of Illinois, Chicago, USA. http://islampapers.com/2012/03/07/moore1/