White communicating rami were traced in 8 human embryos of developmental
stages 14 and 15 (aged 33 and 36 postovulatory days, respectively). In
embryos at stage 14 the white communicating rami were found in the spinal
nerves T1 to T9. In embryos at stage 15 the white communicating rami were
present at the spinal cord levels T1 to L3. (Folia Morphol 2010; 69, 2: 75-77

Bruska, M.

Pytel, A.

Woźniak, W.

Łupicka, J.

English

Via Medica Journals

Folia Morphol. Vol. 69, No. 2, pp. 75–77Copyright © 2010 Via MedicaISSN 0015–5659www.fm.viamedica.plO R I G I N A L    A R T I C L E75Address for correspondence: Prof. M. Bruska, Department of Anatomy, Poznań University of Medical Sciences, Święcickiego 6,60–781 Poznań, Poland, tel: +48 61 854 65 67, fax: +48 61 854 65 68, e-mail: mbruska@ump.edu.plWhite communicating rami in human embryosat the end of the fifth weekM. Bruska, J. Łupicka, A. Pytel, W. WoźniakDepartment of Anatomy, Poznań University of Medical Sciences, Poznań, Poland[Received 10 April 2010; Accepted 27 April 2010]White communicating rami were traced in 8 human embryos of developmen-tal stages 14 and 15 (aged 33 and 36 postovulatory days, respectively). Inembryos at stage 14 the white communicating rami were found in the spinalnerves T1 to T9. In embryos at stage 15 the white communicating rami werepresent at the spinal cord levels T1 to L3. (Folia Morphol 2010; 69, 2: 75–77)Key words: human neuroembryology, white communicating ramiINTRODUCTIONThe final stage of sympathetic development isthe establishment of synaptic connections, which,for sympathetic neurons, can include alternationsin neurotransmitter phenotypes [5].The neurotransmitter features in sympatheticneurons are subject to change during ontogenesis[2]. Studies of sympathetic ontogeny suggested thatcatecholaminergic neural crest derivatives, adrenalchromaffin cells, and sympathetic neurons derivefrom a common sympathoadrenal progenitor [1].In the studied human embryos, aggregation of cellsrepresenting the primordia of the future ganglia ofthe sympathetic trunk is described at different le-vels by several investigators. According to Mitchell[9], such clusters of cells are first evident in the low-er thoracic and upper lumbar regions. The same lo-cation of the first sympathetic ganglia was describedby Kuntz [6, 7]. According to Larsen [8], the sympa-thetic ganglia first form in the cervical region in em-bryos aged 33 days. In our previous paper [18] wedescribed the first appearance of the sympathetictrunk in human embryos at stage 13. They werefound in the thoracic levels T4 to T9. The primordiaof the sympathetic ganglia develop before the ramicommunicantes appear. These rami communicantesare connections between the autonomic centres inthe spinal cord and the paravertebral or preverte-bral ganglia.The development of such rami was presented byPearson and Eckhardt [11]. The authors, however,specify embryonic age based on crown-rump length.The aim of the present study was to describe thewhite communicating rami in staged human em-bryos at the end of the 5th week.MATERIAL AND METHODSSerially sectioned human embryos at stages14 and 15 from the Collection of the Department ofAnatomy at Poznań University of Medical Scienceswere investigated (Table 1).Horizontal sections of 4 embryos at stage 14 and4 at stage 15 were stained with haematoxylin andeosin, according to the Mallory method, and impreg-nated with protargol (Bodian method) and silvergelatin using the method of Pearson and O’Neil.Serial sections of each embryo were examinedmicroscopically and the positions of the rami com-municantes on both sides were evaluated.RESULTSIn embryos of stage 14 the white communicat-ing rami were found at the thoracic level. The upperlimit of these branches was the thoracic level of the76Folia Morphol., 2010, Vol. 69, No. 2Table 1. Crown-rump length (CRL) in mm, developmental stages, age in postovulatory days, and plane of section ofinvestigated embryosCatalogue number of embryo CRL [mm] Stage Age (days) Plane of sectionP-41 5.0 14 33 HorizontalB-207 6.0 14 33 HorizontalA-19 7.0 14 33 CoronalA-17 7.0 14 33 HorizontalB-175 9.0 15 36 HorizontalPJK-20 9.0 15 36 HorizontalA-16 9.0 15 36 HorizontalB-115 8.5 15 36 HorizontalFigure 1. Horizontal section of embryo at stage 14. Haematoxylinand eosin staining; a — spinal ganglion, b — anterior horn ofspinal cord, c — spinal nerve, d — white ramus communicans,e — sympathetic ganglion, f — celiac trunk.Figure 2. Horizontal section of embryo at stage 15. Hematoxylinand eosin staining; a — anterior ramus of spinal nerve,b — white ramus communicans, c — sympathetic ganglion.Figure 3. Horizontal section of embryo at stage 15. Impregnationwith Bodian’s protargol; a — spinal ganglion, b — anterior hornof spinal cord, c — spinal nerve, d — white ramus communi-cans, e — sympathetic ganglion, f — greater thoracic splanchnicnerve, g — mesonephros, h — aorta.Figure 4. Horizontal section of embryo at stage 15. Impregnationwith Bodian’s protargol; a — anterior ramus of spinal nerve,b — white ramus communicans, c – greater thoracic splanchnicnerve, d — mesonephros, e — superior mesenteric artery.77M. Bruska et al., Embryonic white communicating ramifirst thoracic nerve, and the lower level was the ninththoracic nerve (Fig. 1). These branches pass ventral-ly and medially and enter the sympathetic ganglia.In embryos at stage 15 the white communicat-ing rami are present between spinal nerves thoracicone and lumbar two (Figs. 2–4).In the middle and lower thoracic regions thewhite communicating branches split into two bun-dles. One bundle enters the sympathetic trunk gan-glion and a descending bundle runs into the splanch-nic nerves (Figs. 3, 4).DISCUSSIONSympathetic preganglionic neurons occupy theintermediolateral nucleus of the spinal cord, and inhumans these cells are found between the first tho-racic spinal segment and the third lumbar segment[12, 16].The cells within the intermediolateral columnform several subnuclei [3] and show a tendency to-wards segmental aggregation [15]. Experiments inwhich retrograde tracers have been injected intodifferent target organs or ganglia have establishedthat the aggregations represent a viscerotopy [4, 17].There is a rostrocaudal viscerotopic organization tothe distribution [13, 14]. Differentiation of neuronsin the spinal cord proceeds in rostrocaudal and ven-trodorsal gradients [10]. Neurons involved in auto-nomic function show late neurochemical maturation.Axons of preganglionic neurons leave the spinal cordas white communicating rami.Pearson and Eckhardt [11] described white ramiin embryos of 6 and 6.5 mm crown-rump length,and this observation is in agreement with Kuntz.These rami were present in spinal nerves thoracic 3through thoracic 8. Two embryos investigated byPearson and Eckhardt [11] of 7 mm and 8 mmcrown-rump length did not posses any white rami.In our investigations the white communicatingrami were observed at the levels T1 to T9 in all em-bryos at stage 14. During stage 15 such rami werefound at the levels between the first thoracic andthird lumbar. In these embryos the sympathetictrunks extend from the upper cervical to the sacrallevel. Some of the fibres of the white rami pass on-ward to the prevertebral ganglia.Our investigations showed that the white ramicommunicantes, which are connections between thesomatic and autonomic nervous system, developearly in the embryonic period.REFERENCES1. Anderson DJ (1993) Molecular control of cell fate inthe neural crest: the sympathoadrenal lineage. AnnuRev Neurosci, 16: 129–158.2. Anderson R, Morris J, Gibbins IL (2001) Neurochemicaldifferentiation of functionally distinct populations ofautonomic neurons. J Comp Neurol, 429: 419–435.3. Appel NM, Elde RP (1988) The intermediolateral cell co-lumn of the thoracic spinal cord is comprised of target-specific subnuclei: Evidence from retrograde transport stu-dies and immunohistochemistry. J Neurosci, 8: 1767–1775.4. Cabot JB (1990) Sympathetic preganglionic neurons:cytoarchitecture, ultrastructure, and biophysical pro-perties. In: Loewy AD, Spyer KM eds. Central regula-tion of autonomic functions. Oxford University Press,New York, pp. 44–67.5. Francis NJ, Landis SC (1999) Cellular and molecular de-terminants of sympathetic neuron development. AnnuRev Neurosci, 22: 541–566.6. Kuntz A (1920) The development of the sympatheticnervous system in man. J Comp Neurol, 32: 173–231.7. Kuntz A (1953) The autonomic nervous system. Lea andFebiger, Philadelphia.8. Larsen WJ (2001) Human embryology. Churchill Living-stone, New York, Edinburgh, London, Philadelphia.9. Mitchell GAG (1953) Anatomy of the autonomic ner-vous system. Livingstone LTD, Edinburgh, London.10. O’Rahilly R, Müller F (2001) Human embryology andteratology. 3rd Ed, Willey-Liss, New York, Chichester,Weinheim, Brisbone, Singapore, Toronto.11. Pearson AA, Eckhardt AL (1960) Observations on thegray and white rami communicantes in human em-bryos. Anat Rec, 138: 115–127.12. Pick J, Sheehan D (1946) Sympathetic rami in man.J Anat, 80: 12–20.13. Powley TL (1999) Central control of autonomic func-tions. The organization of the autonomic nervous sys-tem. In: Zigmond MJ, Bloom FE, Landis SC, Roberts JL,Squire LR eds. Fundamental neuroscience. AcademicPress, San Diego, London, Boston, New York, Sidney,Tokyo, Toronto, pp. 1027–1050.14. Pyner S, Coote JH (1994) Evidence that sympatheticpreganglionic neurons are arranged in targed-specificcolumns in the thoracic spinal cord of the rat. J CompNeurol, 342: 15–22.15. Rubin E, Purves D (1980) Segmental organization ofsympathetic preganglionic neurons in the mammalianspinal cord. J Comp Neurol, 192: 163–174.16. Sheehan D (1941) Spinal autonomic outflows in manand monkey. J Comp Neurol, 75: 341–370.17. Stark AM, Sayer WB, Marubio LM, Loewy AD (1988)Spinal origin of sympathetic preganglionic neurons inthe rat. Brain Res, 455: 187–191.18. Woźniak W, Grzymisławska M, Łupicka J (2009) Thefirst appearance of sympathetic ganglia in human em-bryos at stage 13. Folia Morphol, 68: 215–217.

White communicating rami in human embryos at the end of the fifth week

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White communicating rami in human embryos at the end of the fifth week

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